WOT Procedure

[rockfangd]

HI all I can never seem to get along with our search section. Maybe it is just me. I am looking for the Woot or WOT procedure for my 96 Deville. My economy is dropping, oil consumption is increasing and I dont think I have been driving it hard enough lately. Thank you

[BodybyFisher]

Ok,

Get onto a local highway where you can increase your speed up to about 75 and where you can drop your speed to about 40 without causing an accident or getting a ticket

Make sure your coolant and oil levels are good

Put your gear selector in 2, your rpms will rise

Press your gas pedal about 3/4 of the way and accelerate till you hit your redline of about 5800. If you are like me, you will chicken out and stop accelerating at about 5000 rpm

The engine is in a low gear, so take your foot off the gas, and the tranny will haul the car down

Let the car show to about 40,

Do 10 cycles, I did this once a month or so,

There are a few things happening here, the high rpms exercises the rings, loosening the carbon in the rings and combustion chamber, the negative pressure created in the combustion chamber by the forced deceleration, blows the loosened carbon out the exhaust

[rockfangd]

thank you for the speedy response.

Now should I be worried with doing this procedure as I am approching 200,000 miles. I have to be honest I baby my cars and try not to drive them too hard.

I guess I cannot complain. I have 32%oil life remaining and this is the first time I am having to add oil. For the first time yesterday it told me to check the oil level. I am running castrol GTX HM 10w30 with ac delco filter. I usually run mobil 1 but when my last oil change was due I couldnt afford it. It would have been 52.00 for oil . Honestly I very rarely open the hood on this car as it runs flawlessly, luckily I can knock on my wood dash lol

[BodybyFisher]

Well I understand your concerns, I have the same apprehensions, its not like I am stressing a new Northstar platform

Don't take it up to 5800 if you are concerned get to 70 then drop to 40, you get ring exercise and negative pressure

The exercise will be good for your engine, you will see

Especially if you baby it, which we have been told is NOT a good thing for this engine

[rockfangd]

Well I understand your concerns, I have the same apprehensions, its not like I am stressing a new Northstar platform

Don't take it up to 5800 if you are concerned get to 70 then drop to 40, you get ring exercise and negative pressure

The exercise will be good for your engine, you will see

Especially if you baby it, which we have been told is NOT a good thing for this engine

I will do this tomorrow morning once I am sure that my oil level is ok.and will post my results. Thanks again

[winterset]

Personally, I am an advocate of Marvel Mystery oil (8oz per tankfull). I make a mental note every once in a while to just ride the car a little hard (hard acceleration getting ono a highway). I look at the rear view mirror for signs of smoke. If I don't see any, I ride it normal for a few more weeks. Seems the MMO helps clean the carbon out without WITH I BELIEVE TO BE less stress on my headbolts. I believe WOT is a little stressful on a 15 year old engine with a design history of headbolt failures.

Correct me if I am wrong, but carbon does not significantlly affect gas mileage, but WOT is mainly to remedy oil consumption caused by carbon buildup sticking the rings.

BTW BBF, I always used the 3/4 throttle too, but seems many believe to just floor it. It read from the guru not to floor it because if forces the transmission to downshift to first gear?

[BodybyFisher]

I believe the PCM will force a shift to stop the engine from passing the red line. I dont ever think that I hit my red line. I do believe that I pulled my bolts with a WOT getting on to a highway, running late to a basketball game.

[JohnnyG]

I don't know how you drive your car on a normal day, but achieving 200,000 miles on an early Northstar without excessive oil consumption is a great accomplishment, and you should be congatulated! You were certainly doing something right!

I'm going to focus on motor oil in this reply and even though I don't think that the Castrol is the cause of your increase in consumption, I'm going to suggest that you go back to whatever oil you were using before at your earliest opportunity. By all means do the WOT procedure as described just to see if that helps.

Better yet, after you finish with the WOT process, get an oil change at your earliest convenience and try to get some of the new standard GF-5 oil into your engine. At this time, only Pennzoil Ultra is saying that it meets GF-5, but Mobil 1 probably does too. I firmly believe that GF-5 was developed in large part with the Northstar engine in mind. I also realize that a former member of this board, a GM Northstar engineer, told us all that the Northstar did not require synthetic oil. However, hearing from people like yourself that have had such excellent results using synthetic, and GM calling for M1 in newer Northstar engines, I cannot help but think that we all may have been better off using Mobil1 right from the start.

AND... Pennzoil is less expensive than M1.

[winterset]

I don't know how you drive your car on a normal day, but achieving 200,000 miles on an early Northstar without excessive oil consumption is a great accomplishment, and you should be congatulated! You were certainly doing something right!

I'm going to focus on motor oil in this reply and even though I don't think that the Castrol is the cause of your increase in consumption, I'm going to suggest that you go back to whatever oil you were using before at your earliest opportunity. By all means do the WOT procedure as described just to see if that helps.

Better yet, after you finish with the WOT process, get an oil change at your earliest convenience and try to get some of the new standard GF-5 oil into your engine. At this time, only Pennzoil Ultra is saying that it meets GF-5, but Mobil 1 probably does too. I firmly believe that GF-5 was developed in large part with the Northstar engine in mind. I also realize that a former member of this board, a GM Northstar engineer, told us all that the Northstar did not require synthetic oil. However, hearing from people like yourself that have had such excellent results using synthetic, and GM calling for M1 in newer Northstar engines, I cannot help but think that we all may have been better off using Mobil1 right from the start.

AND... Pennzoil is less expensive than M1.

My '96 Deville has only seen synthetic Castrol or M1. I was told a few times that it can be the cause of excessive consumptopn. I am not complaining of excessive consumption anymore, but I only have ~107000. I don't use the car much at all now either.

[JimD]

Slightly off-topic for WOT therapy techniques....

....I do believe that I pulled my bolts with a WOT getting on to a highway, running late to a basketball game.

Mike, Mike, Mike. I'm going to challenge that belief (again).

Laying the blame for head gasket failure on head bolt threads remains an undocumented urban myth. I have not heard of or seen reports or suggestions from metallurgical engineers that supports the first domino to fall was the head bolt threads. And my position does not ignore or minimize the fact that GM adjusted the head bolt thread length and pitch several times since 2000.

It just grinds on my eyes everytime I read someone say "pulled head bolts" was the cause of head gasket failure.

Cheers.....

[BodybyFisher]

Jim, please explain, what caused my head gasket to fail then?, did the head gasket breach?

[JimD]

Jim, please explain, what caused my head gasket to fail then?, did the head gasket breach?

You were convinced that your coolant loss was due to failed head gasket(s). Your decision was to not pour more $$ and labor into the repair. In your case, we will never know how/where the head gasket(s) failed.

But there are several (many?) possible places a head gasket can/will fail. One is the seal around the combustion chamber. The result is predictable and immediate.

Another is the seal around the bolt hole. Since the bolt hole is designed to be "dry", allowing acidic coolant into a bolt hole is going to promote/accelerate/increase the expected galvanic action between a ferrous bolt and an aluminum block. The result will not be immediate.

In the case of the bolt hole seal failure, there will be evidence of oxidation when the head bolts are removed for repair. And if whoever is doing the repair does not carefully inspect the failed gasket, we can never know what is cause and what is result.

[rockfangd]

It is hard to say how I treat my cars. I drive them reasonably in a way that is respectful to me, kind of like not slamming the doors, hood, and trunk.

Typically my cars sseem to be flawless due to the fact of how I drive and operate them. such as OEM parts, quality labor. no cheap parts.

I treat my vehicles with nothing but pride and respect and therefore frown on someone who disrespects my hard work.

I have a hard time selling my vehicles because I am always afraid that the vehicle will not be cared for.

Maybe I have issues but my 90 Scottsdale has 165,000 miles and runs and dives like new, and my 96 Deville with 194000 miles still runs and drives like a powerful expensive luxury car.

I cannot complain not one bit

[JohnnyG]

My '96 Deville has only seen synthetic Castrol or M1. I was told a few times that it can be the cause of excessive consumptopn. I am not complaining of excessive consumption anymore, but I only have ~107000. I don't use the car much at all now either.

Winterset, it is unlikely that M1 caused you oil consumption issues, most likely manufacturing tolerances if you want to sum it up to a few words. Check this link below or do a search yourself to see what I mean about the future of motor oils.

Rockfangd, I respect your tendancy to baby your car, and have had a few that I regretted parting with, but remember that the Northstar IS a high performance engine, getting your foot into it every once in a while is not a bad idea.

Check out this link for more info on GF-5 and the upcoming SN standard for motor oil. The new standards not only address piston ring deposits, but our therotertical move to higher and higer concentrations of ethanol in our fuel. 15% to 20% ethanol is coming, and it brings its own set of issues along with it.

http://www.infineum.com/Pages/gf5-11.aspx

[Jan Olsson]

These are multiple passages written by the guru, he was involved with the development of the Northstar.

Northstar Oil Consumption

"It is not unusual for a Northstar to use more oil than some other engines. It is a high performance engine and has to allow a little more oil to the top rings for lube as as well as down the 32 valve guides.

Design intent for oil consumption would put the engine at about 4000 miles per quart consumption but due to the variables in production parameters there are engines that will use 1 quart per 1000-1500 miles.... perfectly normal and acceptable... but more oil consumption than "intended". Nothing will be wrong with the engine but the continuous oil adds are aggravating. If this is the case then understand that the engine is probably going to run a long long time like that as the cylinder walls , rings, valve guides, etc. like all that oil that you are putting in and the continuous oil adds fortify the used oil in the sump and replenish the additive package in the oil that is slowly depleted under normal usage.

Comparing the 4.9 to the Northstar is an apples to oranges deal. The 4.9 is an excellent engine for it's purpose but does not offer nearly the performance, durability, fuel economy and emission control capability of the Northstar. The Northstar is a high output engine and likes to be "used".

The best way to minimize oil consumption in a Northstar is to keep the sump filled slightly low (many are continuously overfilled) by only checking the oil level when hot and only filling the sump with 7 quarts of oil (7.5 with a dry filter at a change.) A typical 8 quart fill at a change is "required" to put the oil level on the full mark when cold but is actually overfilling the crankcase promoting oil consumption.

Use conventional mineral oil (synthetic is not required at all) as it tends to provide better oil consumption.

And last, but not least, air the engine out frequently. It likes to be used and red-line upshifts at WOT help promote clean combustion chambers, exercise the piston rings to keep them free of carbon buildup and keep them mobile and to ensure the engine is broken in and maximum sealing is obtained. The Northstar does not like to be babied around. It likes to be run hard frequently with a WOT blast in merging or whatever.... Even engines reported to use 1 quart per 1500 miles tend to improve to 2500 miles per quart or better when subjected to a regular schedule of use and "abuse"...

----------

The subject of oil consumption really does not have a "final" answer. The fact is that there is some variability in oil consumption in all production engines.... regardless of who makes them on which continent. All the manufacturers recognize this and virtually all of them will call oil consumption as great as 1 quart in 1000 miles "normal" "acceptable" "allowable" "within production tolerances" etc... This doesn't mean that all engines will get 1000 MPQ or that the engine was designed to get 1000 MPQ...it just recognizes the fact that there are going to be some engines that get 1000 MPQ that will be perfectly fine upon disassembly and will have nothing "wrong" with them.

The variables that usually enter into oil consumption are primarily associated with the piston/ring/cylinder bore. The number of valves or type of valve actuation has little to do with it.

The single biggest variable and the one that has been discussed at great length on this forum is the cylinder bore finish or the cylinder honing pattern. The higher performance the engine is the more attention must be paid to the honing pattern and retention of oil on the cylinder walls to lubricate the piston and rings at full load , high RPM operation. The Northstar engine uses a very aggressive cylinder bore finish that tends to retain a lot of oil to protect the piston and rings. When the blocks are honed at the factory there is a tolerance in the bore finish due to the fact that the honing stones will wear and need replacement. A brand new stone gives a slightly more aggressive pattern than a "used" stone....so a block honed with new stones will have a more aggressive finish and most likely will use more oil.

Another variable is bore roundness. Like it or not, the bores tend to "move" slightly as the engine heats up and cools down and bolt tensions relax, etc. over time. All this contributes to slight bore out of roundness that is not bad or good...just different.

Carbon buildup in the rings and ring sealing are also variables that come into play with break in, operating schedule, type of oil used, etc.

The one thing that I can attest to is that many, many customer oil consumption complaint engines have been torn down with absolutely nothing wrong found. The engines are often reassembled and put into test cars and driven by the engineers and more often than not the high oil consumption does not repeat itself !!! The single biggest common cause seems to be breakin...or lack there of. Many, many oil consuming NOrthstar engines are "fixed" by some full throttle operation. I often joke about "driving it like you stole it" but it really is no joke. The Northstar engine was designed as a high performance engine to be run hard and fast. Those that are run hard typically exhibit excellent ring seal, little carbon build up and good oil economy. We have seen engines with tens of thousands of miles on them that the rings have not sealed or mated to the sides of the ring grooves because the operating schedule was so light duty. The moral here is to flog it .... often.

In any case, the nice thing about the engines with the more aggressive honing pattern is that the pistons, rings and bores will last forever. It is very common to tear down a 200,000 mile Northstar engine and still see the original honing pattern in the cylinders. There is never any sign of cylinder wall wear and the idea of a wear "ridge" at the top of the cylinder bore is something that is laughable on a Northstar.

The other nice thing about a little oil consumption is that it adds tremendous safety factor to the oil change interval. Nothing could be better for the engine than an occasional quart of fresh oil. You can take the worst oil on the market and add a fresh quart every 1000 miles and over the life of the engine the wear will be better than an engine run on the best oil with no adds between changes.

While no one in the engineering community wants high oil consumption the fact is that there is some variability in the oil consumption of an engine manufactured at the rate of 1200 per day. The specs of what is "normal" simply reflects this...it does not imply that all engines would get this or that something is wrong with and engine that gets more or less oil consumption.

There have been a lot of engineering changes over the years on the Northstar aimed at reducing the overall oil consumption and reducing the variability in the oil consumption of different engines. Many changes have been made to the honing process to make it more consistent. Changes to the piston and ring groove treatment have been made to make it more resistant to wear, pound out and micro welding at low oil retention rates. Regardless, there is still some variability.

One other thing that affects oil consumption, or the customers perception of oil consumption, is the move toward longer and longer change intervals. With the allowable change interval reaching as high as 12,500 miles on a 2003 Northstar if the oil life monitor is followed this could mean the addition of 3,4 or 5 quarts of oil to a very healthy engine. If the owner changes their oil every 2000 or 3000 miles, despite the oil life monitor recommendations, then they would not have to add any oil between changes. The oil consumption is the same....the amount added between changes is all that is different. Yet, many customers do not make the distinction. Field surveyors repeatedly show that "acceptable" oil consumption means "not having to add between changes"...whatever MPQ that is...???

The issue of oil consumption is very emotional , too, as many people perceive higher oil consumption as 'poor quality" or an indication that something is wrong. Blue smoke, fouling plugs, noise, etc...is a sign of something wrong. Using 1 quart in 1000 miles might be perfectly normal for an engine that has the high limit "rough" hone finish and is perfectly in spec...yet it will be perceived differently.

The Northstar engine in particular was designed to be a high performance engine and to perform well at high speeds and high loads. The engines are tested at loads and speeds for time periods few customers will ever be able to duplicate. It is unfortunate that the engineering that goes into making the engine capable of such running sometimes contributes to more oil consumption... especially as the production machining tolerances are taken into account.

The items mentioned about overfilling also apply. Make sure that the system is not overfilled as any excess oil will be pushed out the PCV. The best bet is to always check the oil hot and keep it midway between the add and full mark. Don't always top off and don't top off cold to the full mark as that will overfill the sump.

Hope this helps rather than adding more fuel to the fire... so to speak.

Incidentally, there is a lot in the message board / forum archives... check using "oil consumption" and read up. Always keep in mind that for every "oil burner" you read about on the internet there are 10,000 or more driving around perfectly fine that the people are not posting about... You are always going to read about the horror cases on the internet".

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Occasional Full-Throttle Acceleration Is Good For Your Engine

There are many advantages to occasional full throttle accelerations with a Northstar and any engine.

It keeps the carbon cleaned out of the combustion chamber. This is maybe a little more important with the Northstar than some other engines due to the tight squish volumes between the piston and the cylinder head. It's designed this way to promote good in-cylinder mixture motion (good combustion) but it has the down side of providing a ready place for carbon build-up to touch the piston - causing noise. Ever heard of the Northstar "cold carbon rap" problem?? Simply put you'll hear a rythmic, piston slap-like noise when the engine is cold. Very prominent and very annoying. Cause: excessive carbon build up causing the the piston to contact the carbon on the head - causing it to rock in the bore and "slap" Much more evident when the engine is cold and the pistons haven't expanded to full diameter yet. Simplest and easiest "fix" for this: A few good WOT (wide open throttle) accelerations to clear the carbon out. That is all it takes to eliminate the problem and prevent it from re-occurring.

Occasional WOT accelerations also help seat the rings to the ring lands and exercise the rings and keep them mobile and from becoming stuck in carbon in the ring lands. At high RPM and WOT the rings move around on the piston - they actually rotate on the piston and will polish away any carbon and seat themselves to the sides of the ring grooves. This is especially important on the 2000 and later Northstars which had hard anodized top ring lands on the pistons. Very hard and wear resistant - also harder to break-in and seat the rings to the sides of the ring-lands to promote the best possible seal. Many oil consumption complaints on the 2000 and later engines are related, to some extent, with the rings never seating to the sides of the ring-grooves due to lack of load as the engine was babied around forever. Even engines with rings stuck in the ring-grooves due to carbon build up can eventually be freed up with enough high RPM operation.

WOTs warm up the engine thoroughly and clean out the exhaust due to temperature in the exhaust and high flow rates blasting particles, rust and such out of the system.

Here is the WOT Procedure

Frequent WOT operation will not hurt the engine or the transmission. They're designed for that. The healthiest engines that I have seen at high miles are always the ones that are run the hardest. Rings are free on the pistons and sealing; no carbon buildup.

The exercise that I think works best for many things is to select manual 2nd gear on an isolated stretch of expressway. This takes the transmission shifting out of the question if you are worried about hurting it. Start at 55 MPH or so and go to WOT in 2nd gear and hold it until the RPM reaches near the normal shift point - i.e. 6500 for an L37 and 6000 for an LD8. Hold the throttle wide open until the engine reaches, say, 6200 for an STS and then just let completely off the throttle. Leave the transmission in 2nd so that the engine brakes the car and creates some pretty heavy over-run conditions at high vacuum levels. Let it slow until it is about 55 or so and then go to WOT again and repeat. This exercise really loads the rings, allows variable RPM operation at WOT for several seconds continuously, creates heavy over-run which tends to unload the rings and make them move and thus exercise them in the ring grooves and it will blow-out carbon and the exhaust - all without creating a spectical of yourself and attracting the attention of cops. You can do it on most any freeway and stay within the 70-75 MPH range allowable. Once a week like this will keep the engine cleaned out and healthy and is DEFINITELY recommended for the Northstar in particular.

The Northstar engine was designed/developed/validated to be run hard. It was expected that people would use the performance of the engine - which few people seem to do. The biggest single problem that many issues stem from is lack of use at full throttle by the owners. It just doesn't like to be babied around. The rings are low-tension by design for good high RPM operating characteristics and low friction/good power. They work best if "used" and kept free.

In every conversation with owners I have had, once the owner started doing the WOTs and using the power of the engine they report no more carbon rap, better oil economy, no "smoke" when they do light it up (keep the exhaust cleaned out. If you notice a "cloud" at WOT then you are not doing enough WOTs...) etc... A bit of judicious use of the other end of the throttle travel is a GOOD thing...

And for the WOTs.

Do as he tells you

Start at 55 MPH or so and go to WOT in 2nd gear and hold it until the RPM reaches near the normal shift point - i.e. 6500 for an L37 and 6000 for an LD8. Hold the throttle wide open until the engine reaches, say, 6200 for an STS and then just let completely off the throttle. Leave the transmission in 2nd so that the engine brakes the car and creates some pretty heavy over-run conditions at high vacuum levels. Let it slow until it is about 55 or so and then go to WOT again and repeat.

[Jan Olsson]

BBF

It's absolutely certain that the high rpms finally did make you gasket blow. A higher load on the engine from power output i.e. combustion pressure, thermal loads and water pressure.

But then again it would only have lasted a couple of days or weeks more.

Don't be afraid of the throttle

And I have to agree with JimD.

Remember James Thomas Smith?

The guru explained why there wasn't a possibility for him to have galvanic corrosion.

The bolt holes are sealed up, no electrical currents "helps" the process and aluminium oxide passivates the surface and prevent continued corrosion which is the direct opposite case with steel/iron. After 50 years perhaps

I still believe that the gaskets blow and thus making the clamping force reach critically low numbers which makes the bolts come loose.

I have seen a lot of pictures of "pulled bolts" and they all show bolts with aluminium in the threads which is what you would expect from a highly loaded bolt removed after a couple of years.

I believe that many people think that the threads following out is a proof, but it looked the same way on my head-bolts when I replaced a burned exhaust valve on my -93 STS, no leaks, no loose bolts.

[CarlaValentine]

These are multiple passages written by the guru, he was involved with the development of the Northstar.

Northstar Oil Consumption

"It is not unusual for a Northstar to use more oil than some other engines. It is a high performance engine and has to allow a little more oil to the top rings for lube as as well as down the 32 valve guides.

Design intent for oil consumption would put the engine at about 4000 miles per quart consumption but due to the variables in production parameters there are engines that will use 1 quart per 1000-1500 miles.... perfectly normal and acceptable... but more oil consumption than "intended". Nothing will be wrong with the engine but the continuous oil adds are aggravating. If this is the case then understand that the engine is probably going to run a long long time like that as the cylinder walls , rings, valve guides, etc. like all that oil that you are putting in and the continuous oil adds fortify the used oil in the sump and replenish the additive package in the oil that is slowly depleted under normal usage.

Comparing the 4.9 to the Northstar is an apples to oranges deal. The 4.9 is an excellent engine for it's purpose but does not offer nearly the performance, durability, fuel economy and emission control capability of the Northstar. The Northstar is a high output engine and likes to be "used".

The best way to minimize oil consumption in a Northstar is to keep the sump filled slightly low (many are continuously overfilled) by only checking the oil level when hot and only filling the sump with 7 quarts of oil (7.5 with a dry filter at a change.) A typical 8 quart fill at a change is "required" to put the oil level on the full mark when cold but is actually overfilling the crankcase promoting oil consumption.

Use conventional mineral oil (synthetic is not required at all) as it tends to provide better oil consumption.

And last, but not least, air the engine out frequently. It likes to be used and red-line upshifts at WOT help promote clean combustion chambers, exercise the piston rings to keep them free of carbon buildup and keep them mobile and to ensure the engine is broken in and maximum sealing is obtained. The Northstar does not like to be babied around. It likes to be run hard frequently with a WOT blast in merging or whatever.... Even engines reported to use 1 quart per 1500 miles tend to improve to 2500 miles per quart or better when subjected to a regular schedule of use and "abuse"...

----------

The subject of oil consumption really does not have a "final" answer. The fact is that there is some variability in oil consumption in all production engines.... regardless of who makes them on which continent. All the manufacturers recognize this and virtually all of them will call oil consumption as great as 1 quart in 1000 miles "normal" "acceptable" "allowable" "within production tolerances" etc... This doesn't mean that all engines will get 1000 MPQ or that the engine was designed to get 1000 MPQ...it just recognizes the fact that there are going to be some engines that get 1000 MPQ that will be perfectly fine upon disassembly and will have nothing "wrong" with them.

The variables that usually enter into oil consumption are primarily associated with the piston/ring/cylinder bore. The number of valves or type of valve actuation has little to do with it.

The single biggest variable and the one that has been discussed at great length on this forum is the cylinder bore finish or the cylinder honing pattern. The higher performance the engine is the more attention must be paid to the honing pattern and retention of oil on the cylinder walls to lubricate the piston and rings at full load , high RPM operation. The Northstar engine uses a very aggressive cylinder bore finish that tends to retain a lot of oil to protect the piston and rings. When the blocks are honed at the factory there is a tolerance in the bore finish due to the fact that the honing stones will wear and need replacement. A brand new stone gives a slightly more aggressive pattern than a "used" stone....so a block honed with new stones will have a more aggressive finish and most likely will use more oil.

Another variable is bore roundness. Like it or not, the bores tend to "move" slightly as the engine heats up and cools down and bolt tensions relax, etc. over time. All this contributes to slight bore out of roundness that is not bad or good...just different.

Carbon buildup in the rings and ring sealing are also variables that come into play with break in, operating schedule, type of oil used, etc.

The one thing that I can attest to is that many, many customer oil consumption complaint engines have been torn down with absolutely nothing wrong found. The engines are often reassembled and put into test cars and driven by the engineers and more often than not the high oil consumption does not repeat itself !!! The single biggest common cause seems to be breakin...or lack there of. Many, many oil consuming NOrthstar engines are "fixed" by some full throttle operation. I often joke about "driving it like you stole it" but it really is no joke. The Northstar engine was designed as a high performance engine to be run hard and fast. Those that are run hard typically exhibit excellent ring seal, little carbon build up and good oil economy. We have seen engines with tens of thousands of miles on them that the rings have not sealed or mated to the sides of the ring grooves because the operating schedule was so light duty. The moral here is to flog it .... often.

In any case, the nice thing about the engines with the more aggressive honing pattern is that the pistons, rings and bores will last forever. It is very common to tear down a 200,000 mile Northstar engine and still see the original honing pattern in the cylinders. There is never any sign of cylinder wall wear and the idea of a wear "ridge" at the top of the cylinder bore is something that is laughable on a Northstar.

The other nice thing about a little oil consumption is that it adds tremendous safety factor to the oil change interval. Nothing could be better for the engine than an occasional quart of fresh oil. You can take the worst oil on the market and add a fresh quart every 1000 miles and over the life of the engine the wear will be better than an engine run on the best oil with no adds between changes.

While no one in the engineering community wants high oil consumption the fact is that there is some variability in the oil consumption of an engine manufactured at the rate of 1200 per day. The specs of what is "normal" simply reflects this...it does not imply that all engines would get this or that something is wrong with and engine that gets more or less oil consumption.

There have been a lot of engineering changes over the years on the Northstar aimed at reducing the overall oil consumption and reducing the variability in the oil consumption of different engines. Many changes have been made to the honing process to make it more consistent. Changes to the piston and ring groove treatment have been made to make it more resistant to wear, pound out and micro welding at low oil retention rates. Regardless, there is still some variability.

One other thing that affects oil consumption, or the customers perception of oil consumption, is the move toward longer and longer change intervals. With the allowable change interval reaching as high as 12,500 miles on a 2003 Northstar if the oil life monitor is followed this could mean the addition of 3,4 or 5 quarts of oil to a very healthy engine. If the owner changes their oil every 2000 or 3000 miles, despite the oil life monitor recommendations, then they would not have to add any oil between changes. The oil consumption is the same....the amount added between changes is all that is different. Yet, many customers do not make the distinction. Field surveyors repeatedly show that "acceptable" oil consumption means "not having to add between changes"...whatever MPQ that is...???

The issue of oil consumption is very emotional , too, as many people perceive higher oil consumption as 'poor quality" or an indication that something is wrong. Blue smoke, fouling plugs, noise, etc...is a sign of something wrong. Using 1 quart in 1000 miles might be perfectly normal for an engine that has the high limit "rough" hone finish and is perfectly in spec...yet it will be perceived differently.

The Northstar engine in particular was designed to be a high performance engine and to perform well at high speeds and high loads. The engines are tested at loads and speeds for time periods few customers will ever be able to duplicate. It is unfortunate that the engineering that goes into making the engine capable of such running sometimes contributes to more oil consumption... especially as the production machining tolerances are taken into account.

The items mentioned about overfilling also apply. Make sure that the system is not overfilled as any excess oil will be pushed out the PCV. The best bet is to always check the oil hot and keep it midway between the add and full mark. Don't always top off and don't top off cold to the full mark as that will overfill the sump.

Hope this helps rather than adding more fuel to the fire... so to speak.

Incidentally, there is a lot in the message board / forum archives... check using "oil consumption" and read up. Always keep in mind that for every "oil burner" you read about on the internet there are 10,000 or more driving around perfectly fine that the people are not posting about... You are always going to read about the horror cases on the internet".

--------------------------------------------------------------------------

Occasional Full-Throttle Acceleration Is Good For Your Engine

There are many advantages to occasional full throttle accelerations with a Northstar and any engine.

It keeps the carbon cleaned out of the combustion chamber. This is maybe a little more important with the Northstar than some other engines due to the tight squish volumes between the piston and the cylinder head. It's designed this way to promote good in-cylinder mixture motion (good combustion) but it has the down side of providing a ready place for carbon build-up to touch the piston - causing noise. Ever heard of the Northstar "cold carbon rap" problem?? Simply put you'll hear a rythmic, piston slap-like noise when the engine is cold. Very prominent and very annoying. Cause: excessive carbon build up causing the the piston to contact the carbon on the head - causing it to rock in the bore and "slap" Much more evident when the engine is cold and the pistons haven't expanded to full diameter yet. Simplest and easiest "fix" for this: A few good WOT (wide open throttle) accelerations to clear the carbon out. That is all it takes to eliminate the problem and prevent it from re-occurring.

Occasional WOT accelerations also help seat the rings to the ring lands and exercise the rings and keep them mobile and from becoming stuck in carbon in the ring lands. At high RPM and WOT the rings move around on the piston - they actually rotate on the piston and will polish away any carbon and seat themselves to the sides of the ring grooves. This is especially important on the 2000 and later Northstars which had hard anodized top ring lands on the pistons. Very hard and wear resistant - also harder to break-in and seat the rings to the sides of the ring-lands to promote the best possible seal. Many oil consumption complaints on the 2000 and later engines are related, to some extent, with the rings never seating to the sides of the ring-grooves due to lack of load as the engine was babied around forever. Even engines with rings stuck in the ring-grooves due to carbon build up can eventually be freed up with enough high RPM operation.

WOTs warm up the engine thoroughly and clean out the exhaust due to temperature in the exhaust and high flow rates blasting particles, rust and such out of the system.

Here is the WOT Procedure

Frequent WOT operation will not hurt the engine or the transmission. They're designed for that. The healthiest engines that I have seen at high miles are always the ones that are run the hardest. Rings are free on the pistons and sealing; no carbon buildup.

The exercise that I think works best for many things is to select manual 2nd gear on an isolated stretch of expressway. This takes the transmission shifting out of the question if you are worried about hurting it. Start at 55 MPH or so and go to WOT in 2nd gear and hold it until the RPM reaches near the normal shift point - i.e. 6500 for an L37 and 6000 for an LD8. Hold the throttle wide open until the engine reaches, say, 6200 for an STS and then just let completely off the throttle. Leave the transmission in 2nd so that the engine brakes the car and creates some pretty heavy over-run conditions at high vacuum levels. Let it slow until it is about 55 or so and then go to WOT again and repeat. This exercise really loads the rings, allows variable RPM operation at WOT for several seconds continuously, creates heavy over-run which tends to unload the rings and make them move and thus exercise them in the ring grooves and it will blow-out carbon and the exhaust - all without creating a spectical of yourself and attracting the attention of cops. You can do it on most any freeway and stay within the 70-75 MPH range allowable. Once a week like this will keep the engine cleaned out and healthy and is DEFINITELY recommended for the Northstar in particular.

The Northstar engine was designed/developed/validated to be run hard. It was expected that people would use the performance of the engine - which few people seem to do. The biggest single problem that many issues stem from is lack of use at full throttle by the owners. It just doesn't like to be babied around. The rings are low-tension by design for good high RPM operating characteristics and low friction/good power. They work best if "used" and kept free.

In every conversation with owners I have had, once the owner started doing the WOTs and using the power of the engine they report no more carbon rap, better oil economy, no "smoke" when they do light it up (keep the exhaust cleaned out. If you notice a "cloud" at WOT then you are not doing enough WOTs...) etc... A bit of judicious use of the other end of the throttle travel is a GOOD thing...

And for the WOTs.

Do as he tells you

Start at 55 MPH or so and go to WOT in 2nd gear and hold it until the RPM reaches near the normal shift point - i.e. 6500 for an L37 and 6000 for an LD8. Hold the throttle wide open until the engine reaches, say, 6200 for an STS and then just let completely off the throttle. Leave the transmission in 2nd so that the engine brakes the car and creates some pretty heavy over-run conditions at high vacuum levels. Let it slow until it is about 55 or so and then go to WOT again and repeat.

Thanks for posting this! I never got to talk to the Guru so I love reading anything he has had to say.

[winterset]

My understanding why dentists use silver for fillings was that the expansion and contraction of our teeth was closest to the metal. If a material used has too much of a delta between expansion rates of our natural teeth, overtime drinking hot tea, or drinking cold milk will slowly cause the materials to unbond & become loose. Makes me wonder if the whole headgasket failure is just something that happens to the gaskets because of this constant contraction between all these different metals (steel bolts contracting & expanding more or less than the aluminum case & gasket material.) - where overtime, the gaskets just give. When a gasket is newer & healthy, it can expand & contract enough to keep the seal, but as it gets worn from something like neglected coolant & age, it slowly developes weak points, and just gives out eventually. It's why I keep up with my coolant & add the barrs stop leak as recommended by GM. If I do have a micro weak point forming, hopefully the Baars plugs it up & keep it from getting any worse. I have seen photos on this site that showed the stop leak working it's way into failing gasket material.

[rockfangd]

These are multiple passages written by the guru, he was involved with the development of the Northstar.

Northstar Oil Consumption

"It is not unusual for a Northstar to use more oil than some other engines. It is a high performance engine and has to allow a little more oil to the top rings for lube as as well as down the 32 valve guides.

Design intent for oil consumption would put the engine at about 4000 miles per quart consumption but due to the variables in production parameters there are engines that will use 1 quart per 1000-1500 miles.... perfectly normal and acceptable... but more oil consumption than "intended". Nothing will be wrong with the engine but the continuous oil adds are aggravating. If this is the case then understand that the engine is probably going to run a long long time like that as the cylinder walls , rings, valve guides, etc. like all that oil that you are putting in and the continuous oil adds fortify the used oil in the sump and replenish the additive package in the oil that is slowly depleted under normal usage.

Comparing the 4.9 to the Northstar is an apples to oranges deal. The 4.9 is an excellent engine for it's purpose but does not offer nearly the performance, durability, fuel economy and emission control capability of the Northstar. The Northstar is a high output engine and likes to be "used".

The best way to minimize oil consumption in a Northstar is to keep the sump filled slightly low (many are continuously overfilled) by only checking the oil level when hot and only filling the sump with 7 quarts of oil (7.5 with a dry filter at a change.) A typical 8 quart fill at a change is "required" to put the oil level on the full mark when cold but is actually overfilling the crankcase promoting oil consumption.

Use conventional mineral oil (synthetic is not required at all) as it tends to provide better oil consumption.

And last, but not least, air the engine out frequently. It likes to be used and red-line upshifts at WOT help promote clean combustion chambers, exercise the piston rings to keep them free of carbon buildup and keep them mobile and to ensure the engine is broken in and maximum sealing is obtained. The Northstar does not like to be babied around. It likes to be run hard frequently with a WOT blast in merging or whatever.... Even engines reported to use 1 quart per 1500 miles tend to improve to 2500 miles per quart or better when subjected to a regular schedule of use and "abuse"...

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The subject of oil consumption really does not have a "final" answer. The fact is that there is some variability in oil consumption in all production engines.... regardless of who makes them on which continent. All the manufacturers recognize this and virtually all of them will call oil consumption as great as 1 quart in 1000 miles "normal" "acceptable" "allowable" "within production tolerances" etc... This doesn't mean that all engines will get 1000 MPQ or that the engine was designed to get 1000 MPQ...it just recognizes the fact that there are going to be some engines that get 1000 MPQ that will be perfectly fine upon disassembly and will have nothing "wrong" with them.

The variables that usually enter into oil consumption are primarily associated with the piston/ring/cylinder bore. The number of valves or type of valve actuation has little to do with it.

The single biggest variable and the one that has been discussed at great length on this forum is the cylinder bore finish or the cylinder honing pattern. The higher performance the engine is the more attention must be paid to the honing pattern and retention of oil on the cylinder walls to lubricate the piston and rings at full load , high RPM operation. The Northstar engine uses a very aggressive cylinder bore finish that tends to retain a lot of oil to protect the piston and rings. When the blocks are honed at the factory there is a tolerance in the bore finish due to the fact that the honing stones will wear and need replacement. A brand new stone gives a slightly more aggressive pattern than a "used" stone....so a block honed with new stones will have a more aggressive finish and most likely will use more oil.

Another variable is bore roundness. Like it or not, the bores tend to "move" slightly as the engine heats up and cools down and bolt tensions relax, etc. over time. All this contributes to slight bore out of roundness that is not bad or good...just different.

Carbon buildup in the rings and ring sealing are also variables that come into play with break in, operating schedule, type of oil used, etc.

The one thing that I can attest to is that many, many customer oil consumption complaint engines have been torn down with absolutely nothing wrong found. The engines are often reassembled and put into test cars and driven by the engineers and more often than not the high oil consumption does not repeat itself !!! The single biggest common cause seems to be breakin...or lack there of. Many, many oil consuming NOrthstar engines are "fixed" by some full throttle operation. I often joke about "driving it like you stole it" but it really is no joke. The Northstar engine was designed as a high performance engine to be run hard and fast. Those that are run hard typically exhibit excellent ring seal, little carbon build up and good oil economy. We have seen engines with tens of thousands of miles on them that the rings have not sealed or mated to the sides of the ring grooves because the operating schedule was so light duty. The moral here is to flog it .... often.

In any case, the nice thing about the engines with the more aggressive honing pattern is that the pistons, rings and bores will last forever. It is very common to tear down a 200,000 mile Northstar engine and still see the original honing pattern in the cylinders. There is never any sign of cylinder wall wear and the idea of a wear "ridge" at the top of the cylinder bore is something that is laughable on a Northstar.

The other nice thing about a little oil consumption is that it adds tremendous safety factor to the oil change interval. Nothing could be better for the engine than an occasional quart of fresh oil. You can take the worst oil on the market and add a fresh quart every 1000 miles and over the life of the engine the wear will be better than an engine run on the best oil with no adds between changes.

While no one in the engineering community wants high oil consumption the fact is that there is some variability in the oil consumption of an engine manufactured at the rate of 1200 per day. The specs of what is "normal" simply reflects this...it does not imply that all engines would get this or that something is wrong with and engine that gets more or less oil consumption.

There have been a lot of engineering changes over the years on the Northstar aimed at reducing the overall oil consumption and reducing the variability in the oil consumption of different engines. Many changes have been made to the honing process to make it more consistent. Changes to the piston and ring groove treatment have been made to make it more resistant to wear, pound out and micro welding at low oil retention rates. Regardless, there is still some variability.

One other thing that affects oil consumption, or the customers perception of oil consumption, is the move toward longer and longer change intervals. With the allowable change interval reaching as high as 12,500 miles on a 2003 Northstar if the oil life monitor is followed this could mean the addition of 3,4 or 5 quarts of oil to a very healthy engine. If the owner changes their oil every 2000 or 3000 miles, despite the oil life monitor recommendations, then they would not have to add any oil between changes. The oil consumption is the same....the amount added between changes is all that is different. Yet, many customers do not make the distinction. Field surveyors repeatedly show that "acceptable" oil consumption means "not having to add between changes"...whatever MPQ that is...???

The issue of oil consumption is very emotional , too, as many people perceive higher oil consumption as 'poor quality" or an indication that something is wrong. Blue smoke, fouling plugs, noise, etc...is a sign of something wrong. Using 1 quart in 1000 miles might be perfectly normal for an engine that has the high limit "rough" hone finish and is perfectly in spec...yet it will be perceived differently.

The Northstar engine in particular was designed to be a high performance engine and to perform well at high speeds and high loads. The engines are tested at loads and speeds for time periods few customers will ever be able to duplicate. It is unfortunate that the engineering that goes into making the engine capable of such running sometimes contributes to more oil consumption... especially as the production machining tolerances are taken into account.

The items mentioned about overfilling also apply. Make sure that the system is not overfilled as any excess oil will be pushed out the PCV. The best bet is to always check the oil hot and keep it midway between the add and full mark. Don't always top off and don't top off cold to the full mark as that will overfill the sump.

Hope this helps rather than adding more fuel to the fire... so to speak.

Incidentally, there is a lot in the message board / forum archives... check using "oil consumption" and read up. Always keep in mind that for every "oil burner" you read about on the internet there are 10,000 or more driving around perfectly fine that the people are not posting about... You are always going to read about the horror cases on the internet".

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Occasional Full-Throttle Acceleration Is Good For Your Engine

There are many advantages to occasional full throttle accelerations with a Northstar and any engine.

It keeps the carbon cleaned out of the combustion chamber. This is maybe a little more important with the Northstar than some other engines due to the tight squish volumes between the piston and the cylinder head. It's designed this way to promote good in-cylinder mixture motion (good combustion) but it has the down side of providing a ready place for carbon build-up to touch the piston - causing noise. Ever heard of the Northstar "cold carbon rap" problem?? Simply put you'll hear a rythmic, piston slap-like noise when the engine is cold. Very prominent and very annoying. Cause: excessive carbon build up causing the the piston to contact the carbon on the head - causing it to rock in the bore and "slap" Much more evident when the engine is cold and the pistons haven't expanded to full diameter yet. Simplest and easiest "fix" for this: A few good WOT (wide open throttle) accelerations to clear the carbon out. That is all it takes to eliminate the problem and prevent it from re-occurring.

Occasional WOT accelerations also help seat the rings to the ring lands and exercise the rings and keep them mobile and from becoming stuck in carbon in the ring lands. At high RPM and WOT the rings move around on the piston - they actually rotate on the piston and will polish away any carbon and seat themselves to the sides of the ring grooves. This is especially important on the 2000 and later Northstars which had hard anodized top ring lands on the pistons. Very hard and wear resistant - also harder to break-in and seat the rings to the sides of the ring-lands to promote the best possible seal. Many oil consumption complaints on the 2000 and later engines are related, to some extent, with the rings never seating to the sides of the ring-grooves due to lack of load as the engine was babied around forever. Even engines with rings stuck in the ring-grooves due to carbon build up can eventually be freed up with enough high RPM operation.

WOTs warm up the engine thoroughly and clean out the exhaust due to temperature in the exhaust and high flow rates blasting particles, rust and such out of the system.

Here is the WOT Procedure

Frequent WOT operation will not hurt the engine or the transmission. They're designed for that. The healthiest engines that I have seen at high miles are always the ones that are run the hardest. Rings are free on the pistons and sealing; no carbon buildup.

The exercise that I think works best for many things is to select manual 2nd gear on an isolated stretch of expressway. This takes the transmission shifting out of the question if you are worried about hurting it. Start at 55 MPH or so and go to WOT in 2nd gear and hold it until the RPM reaches near the normal shift point - i.e. 6500 for an L37 and 6000 for an LD8. Hold the throttle wide open until the engine reaches, say, 6200 for an STS and then just let completely off the throttle. Leave the transmission in 2nd so that the engine brakes the car and creates some pretty heavy over-run conditions at high vacuum levels. Let it slow until it is about 55 or so and then go to WOT again and repeat. This exercise really loads the rings, allows variable RPM operation at WOT for several seconds continuously, creates heavy over-run which tends to unload the rings and make them move and thus exercise them in the ring grooves and it will blow-out carbon and the exhaust - all without creating a spectical of yourself and attracting the attention of cops. You can do it on most any freeway and stay within the 70-75 MPH range allowable. Once a week like this will keep the engine cleaned out and healthy and is DEFINITELY recommended for the Northstar in particular.

The Northstar engine was designed/developed/validated to be run hard. It was expected that people would use the performance of the engine - which few people seem to do. The biggest single problem that many issues stem from is lack of use at full throttle by the owners. It just doesn't like to be babied around. The rings are low-tension by design for good high RPM operating characteristics and low friction/good power. They work best if "used" and kept free.

In every conversation with owners I have had, once the owner started doing the WOTs and using the power of the engine they report no more carbon rap, better oil economy, no "smoke" when they do light it up (keep the exhaust cleaned out. If you notice a "cloud" at WOT then you are not doing enough WOTs...) etc... A bit of judicious use of the other end of the throttle travel is a GOOD thing...

And for the WOTs.

Do as he tells you

Start at 55 MPH or so and go to WOT in 2nd gear and hold it until the RPM reaches near the normal shift point - i.e. 6500 for an L37 and 6000 for an LD8. Hold the throttle wide open until the engine reaches, say, 6200 for an STS and then just let completely off the throttle. Leave the transmission in 2nd so that the engine brakes the car and creates some pretty heavy over-run conditions at high vacuum levels. Let it slow until it is about 55 or so and then go to WOT again and repeat.

thank you for a wonderful document.

Most useful

[Ranger]

Barsleaks sole purpose was to seal possible porous aluminum castings and will do nothing to prevent or cure a head gasket leak.

[rockfangd]

Ok so I did the procedure tonight and It was so easy, I couldnt believe it, I wass at 78 mph 4800 RPM and it still had a lot of power to it, I felt as if I could have done 90mph easily.

Is it normal to get a hard on when hearing a northstar roar, Lol.

Sorry I believe I love my car, It gives me such pleasure when I feed it the fuel it needs.

I did notice one thing, unless it was just me, It seemed like when I restarted the engine it fired about 3 seconds faster than normal, baically it fired up on second turnover instead of the fourth,

Either way if it can do 80 in 2nd gear I could nonly imagine what it could do without a governor.

[BodybyFisher]

YES IT IS, LOL...

And Yes, the WOT is great medicine for your engine, it runs so much better. Also long highway trips are also good for your engine where you will feel a difference afterward

[scott y]

Once or twice a month I go out on the backroads(in the country) and just cruise around in 2nd looking for safe stretches to perform the exercise. I've been known to do it about 10 times before the ol' 94 gets any mercy. Always notice after the old girl gets her exercise that the exhaust note sounds clearer and crisper. She doesn't seem to mind the punishment at all...

[Texas Jim]

Ok so I did the procedure tonight and It was so easy, I couldnt believe it, I wass at 78 mph 4800 RPM and it still had a lot of power to it, I felt as if I could have done 90mph easily.

Is it normal to get a hard on when hearing a northstar roar, Lol.

Sorry I believe I love my car, It gives me such pleasure when I feed it the fuel it needs.

I did notice one thing, unless it was just me, It seemed like when I restarted the engine it fired about 3 seconds faster than normal, baically it fired up on second turnover instead of the fourth,

Either way if it can do 80 in 2nd gear I could only imagine what it could do without a governor.

About your first question...not sure, but I do know that your heart rate will go up as the RPM's go up...

Mine is a VIN 9, so it has a lower final drive ratio than yours but a higher RPM limiter so it is probably about the same in MPH thru the gears.

WOT and letting it shift as it hits redline...

2nd to 3rd...90mph

3rd to 4th...138...

4th top speed....I don't know, but I have seen 144 on it before I had to slow down...and it was still pulling pretty good.. :)

[winterset]

Barsleaks sole purpose was to seal possible porous aluminum castings and will do nothing to prevent or cure a head gasket leak.

Of course never cure, but prevent.... I have my own opinion. If it's purpose is to seal porous aluminum, who's to say that porous aluminum is not in contact with my head gaskets? What I am saying is that I'd like to keep my bolts & gaskets free of coolant. In addition, if the bars although unintentional of the engineers keeps seepage of coolant away around the internals of the gasket - namely the bolts, - then all the better.

I am thinking that if one section of the gasket, and not all gets wet with coolant, it will expand & contract differently from the rest causing uneven stress on the gasket, and eventually failure.