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Oil Consumption


ragingbull27

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Hello Guys, I have a question for anybody who would know....I have a 2003 Cadillac Deville with a northstar engine at 52,000 miles that is going through about 1 quart every 800 miles...I have had the Car tested and everything comes backs that the car is okay...I have tried WOT and still get the same results....My question is this: I have a GMAP 2 year warranty on the car and the cadillac shop told me that they wouldn't start changing the valves or anything that had to do with oil consumption because they cannot Warranty the service, BUT! What they did said was that they would give me a brand new rebuilt Jasper Engine warrantied at 3 years and 100,000 miles. My Question is this: Should I just keep the northstar engine and throw a quart in their every 800 miles OR get the brand new rebuilt? Which would be better for me in a long run.....Any help I would appreciate....Thank You, Ragingbull27

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First off, you are not putting any mileage on that car at all, you are doing about 6500 miles a year

Would you say that you baby the car?

When I first got my Northstar it was driving by a nice old man from North Jersey, in the first couple of months I kept seeing the add oil message

Then I got on to the Long Island Expressway and I did the WOT PROCEDURE and I did it weekly for a month, here is what you do

******************************

Get to an OPEN ROAD with no traffic on it, and good weather conditions, oil reading on the dip stick, coolant level good

Drive 40 mph, put the transmission selector in 2, push the accelerator about 3/4 of the way to the floor and get up to 70,

then let off the gas and let the tranny haul the car down decelerating till you hit 40, then again press the accelerator 3/4 and accelerate to 70,

and again let off the gas, repeat this pattern 10 times

This is called the WOT PROCEDURE, it exercises the rings, blows out carbon, cleans the rings, reseats the rings, etc. The deceleration creates negative pressure in the cylinder and sucks the carbon out of the combustion chamber.

Do this weekly, then monthly, you will see a difference in oil consumption.

You may also stop using synthetic if you are using it, I find its too thin

By the way, dont try to 'get over' on the warranty because its about to end, you may end up in a worse situation then you were before. This engine tends to use oil but you can improve it greatly, have patience

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Here are articles that I have gathered over the years regarding oil consumption of the Northstar. They were written by the guru, he is a design engineer on the Northstar Powertrain team. Some of this may seem disjointed but its because it came from multiple sources, Mike

Northstar Oil Consumption

"It is not unusual for a Northstar to use more oil than some otherengines. It is a high performance engine and has to allow a little more oil tothe 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 perquart consumption but due to the variables in production parameters there areengines that will use 1 quart per 1000-1500 miles.... perfectly normal andacceptable... but more oil consumption than "intended". Nothing willbe wrong with the engine but the continuous oil adds are aggravating. If thisis the case then understand that the engine is probably going to run a longlong time like that as the cylinder walls , rings, valve guides, etc. like allthat oil that you are putting in and the continuous oil adds fortify the usedoil in the sump and replenish the additive package in the oil that is slowlydepleted under normal usage.

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

The best way to minimize oil consumption in a Northstar is to keep the sumpfilled slightly low (many are continuously overfilled) by only checking the oillevel when hot and only filling the sump with 7 quarts of oil (7.5 with a dryfilter 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 thecrankcase promoting oil consumption.

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

An last, but not least, air the engine out frequently. It likes to be used andred-line upshifts at WOT help promote clean combustion chambers, exercise thepiston rings to keep them free of carbon buildup and keep them mobile and toensure the engine is broken in and maximum sealing is obtained. The Northstardoes not like to be babied around. It likes to be run hard frequently with aWOT blast in merging or whatever.... Even engines reported to use 1 quart per1500 miles tend to improve to 2500 miles per quart or better when subjected toa 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 productionengines.... regardless of who makes them on which continent. All themanufacturers recognize this and virtually all of them will call oilconsumption 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 enginewas designed to get 1000 MPQ...it just recognizes the fact that there are goingto be some engines that get 1000 MPQ that will be perfectly fine upondisassembly and will have nothing "wrong" with them.

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

The single biggest variable and the one that has been discussed at great lengthon this forum is the cylinder bore finish or the cylinder honing pattern. Thehigher performance the engine is the more attention must be paid to the honingpattern and retention of oil on the cylinder walls to lubricate the piston andrings at full load , high RPM operation. The Northstar engine uses a veryaggressive cylinder bore finish that tends to retain a lot of oil to protectthe piston and rings. When the blocks are honed at the factory there is atolerance in the bore finish due to the fact that the honing stones will wearand need replacement. A brand new stone gives a slightly more aggressivepattern than a "used" stone....so a block honed with new stones willhave 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 bolttensions relax, etc. over time. All this contributes to slight bore out ofroundness that is not bad or good...just different.

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

The one thing that I can attest to is that many, many customer oil consumptioncomplaint engines have been torn down with absolutely nothing wrong found. Theengines are often reassembled and put into test cars and driven by theengineers and more often than not the high oil consumption does not repeatitself !!! The single biggest common cause seems to be breakin...or lack thereof. Many, many oil consuming NOrthstar engines are "fixed" by somefull throttle operation. I often joke about "driving it like you stoleit" but it really is no joke. The Northstar engine was designed as a highperformance engine to be run hard and fast. Those that are run hard typicallyexhibit excellent ring seal, little carbon build up and good oil economy. Wehave seen engines with tens of thousands of miles on them that the rings havenot sealed or mated to the sides of the ring grooves because the operatingschedule 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 honingpattern is that the pistons, rings and bores will last forever. It is verycommon to tear down a 200,000 mile Northstar engine and still see the originalhoning pattern in the cylinders. There is never any sign of cylinder wall wearand the idea of a wear "ridge" at the top of the cylinder bore issomething that is laughable on a Northstar.

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

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

There have been a lot of engineering changes over the years on the Northstaraimed at reducing the overall oil consumption and reducing the variability inthe oil consumption of different engines. Many changes have been made to thehoning process to make it more consistent. Changes to the piston and ringgroove treatment have been made to make it more resistant to wear, pound outand micro welding at low oil retention rates. Regardless, there is still somevariability.

One other thing that affects oil consumption, or the customers perception ofoil consumption, is the move toward longer and longer change intervals. Withthe allowable change interval reaching as high as 12,500 miles on a 2003Northstar if the oil life monitor is followed this could mean the addition of3,4 or 5 quarts of oil to a very healthy engine. If the owner changes their oilevery 2000 or 3000 miles, despite the oil life monitor recommendations, thenthey would not have to add any oil between changes. The oil consumption is thesame....the amount added between changes is all that is different. Yet, manycustomers do not make the distinction. Field surveyors repeatedly show that"acceptable" oil consumption means "not having to add betweenchanges"...whatever MPQ that is...???

The issue of oil consumption is very emotional , too, as many people perceivehigher oil consumption as 'poor quality" or an indication that somethingis 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 hasthe high limit "rough" hone finish and is perfectly in spec...yet itwill be perceived differently.

The Northstar engine in particular was designed to be a high performance engineand to perform well at high speeds and high loads. The engines are tested atloads 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 capableof such running sometimes contributes to more oil consumption... especially asthe production machining tolerances are taken into account.

The items mentioned about overfilling also apply. Make sure that the system isnot overfilled as any excess oil will be pushed out the PCV. The best bet is toalways 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 willoverfill 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... checkusing "oil consumption" and read up. Always keep in mind that forevery "oil burner" you read about on the internet there are 10,000 ormore driving around perfectly fine that the people are not posting about... Youare 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 aNorthstar and any engine.

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

Occasional WOT accelerations also help seat the rings to the ring lands andexercise the rings and keep them mobile and from becoming stuck in carbon inthe ring lands. At high RPM and WOT the rings move around on the piston - theyactually rotate on the piston and will polish away any carbon and seatthemselves to the sides of the ring grooves. This is especially important onthe 2000 and later Northstars which had hard anodized top ring lands on thepistons. Very hard and wear resistant - also harder to break-in and seat therings to the sides of the ring-lands to promote the best possible seal. Manyoil consumption complaints on the 2000 and later engines are related, to someextent, with the rings never seating to the sides of the ring-grooves due tolack of load as the engine was babied around forever. Even engines with ringsstuck in the ring-grooves due to carbon build up can eventually be freed upwith enough high RPM operation.

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

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

The exercise that I think works best for many things is to select manual 2ndgear on an isolated stretch of expressway. This takes the transmission shiftingout of the question if you are worried about hurting it. Start at 55 MPH or soand go to WOT in 2nd gear and hold it until the RPM reaches near the normalshift point - i.e. 6500 for an L37 and 6000 for an LD8. Hold the throttle wideopen until the engine reaches, say, 6200 for an STS and then just letcompletely off the throttle. Leave the transmission in 2nd so that the enginebrakes the car and creates some pretty heavy over-run conditions at high vacuumlevels. Let it slow until it is about 55 or so and then go to WOT again andrepeat. This exercise really loads the rings, allows variable RPM operation atWOT for several seconds continuously, creates heavy over-run which tends tounload the rings and make them move and thus exercise them in the ring groovesand it will blow-out carbon and the exhaust - all without creating a specticalof yourself and attracting the attention of cops. You can do it on most anyfreeway and stay within the 70-75 MPH range allowable. Once a week like thiswill keep the engine cleaned out and healthy and is DEFINITELY recommended forthe Northstar in particular.

The Northstar engine was designed/developed/validated to be run hard. It wasexpected that people would use the performance of the engine - which few peopleseem to do. The biggest single problem that many issues stem from is lack ofuse 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 characteristicsand 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 theWOTs and using the power of the engine they report no more carbon rap, betteroil economy, no "smoke" when they do light it up (keep the exhaustcleaned out. If you notice a "cloud" at WOT then you are not doingenough WOTs...) etc... A bit of judicious use of the other end of the throttletravel is a GOOD thing...

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First off, you are not putting any mileage on that car at all, you are doing about 6500 miles a year

Would you say that you baby the car?

When I first got my Northstar it was driving by a nice old man from North Jersey, in the first couple of months I kept seeing the add oil message

Then I got on to the Long Island Expressway and I did the WOT PROCEDURE and I did it weekly for a month, here is what you do

******************************

Get to an OPEN ROAD with no traffic on it, and good weather conditions, oil reading on the dip stick, coolant level good

Drive 40 mph, put the transmission selector in 2, push the accelerator about 3/4 of the way to the floor and get up to 70,

then let off the gas and let the tranny haul the car down decelerating till you hit 40, then again press the accelerator 3/4 and accelerate to 70,

and again let off the gas, repeat this pattern 10 times

This is called the WOT PROCEDURE, it exercises the rings, blows out carbon, cleans the rings, reseats the rings, etc. The deceleration creates negative pressure in the cylinder and sucks the carbon out of the combustion chamber.

Do this weekly, then monthly, you will see a difference in oil consumption.

You may also stop using synthetic if you are using it, I find its too thin

By the way, dont try to 'get over' on the warranty because its about to end, you may end up in a worse situation then you were before. This engine tends to use oil but you can improve it greatly, have patience

Thanks BodybyFisher

OK so what your saying is to keep on doing the WOT, which I have been doing, But give it some more time patience.....I do take care of her but I also get on her, I don't drive like an old man, but I also don't drive like a kid.....I put regular oil in her.....Thats exactly right about the mileage.....I bought the Cadillac in Nov 2010 with 46,000 miles on it and it was bought from a older couple who traded in the vehicle at the dealer....Thats why I bought the car figuring that the older couple had babied her and the mileage was low.....I only put on about 6,000 miles since I bought her which is at 52,000 miles right now.....I just want to make sure that it doesn't get any worse before the warranty expires in Nov 2012...I don't want to get stuck paying for another engine......Like I said it not leaking or blowing smoke...It's just go through a quart of oil every 800 miles....But it sounds like you would definitely keep the northstar engine? Right? over the rebuilt jasper engine?....the car runs beautiful and there's no other problems.....I appreciate your help! Thank you very much!!!

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have you tried the woot procedure. I just did it tonight on my Deville and it loves it.

Research woot and if you havent done it yet, do it a few times and see what happens

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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also my honest opinion is there should be no reason to waste a northstar that isnt even broken in yet for a rebuilt engine. sounds kind of funny if you ask me.

Welcome to Caddyinfo

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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hope this helps you

When I bought my 96 Deville a couple years ago it had been babied by the previous owner and waas parked alot. the egr was plugged shut and oil consumption was higher than usual for me being familiar with the engine.

I cleaned out the egr and pipe the first week, the code went away and the SES light has never come back. I drove it like I stole it when i cleaned the egr and the smoke was unbelievable. The more I beat on it the better it got. I drive it like I stole it anytime at all.

I absolutely do not recommend idle time. If a passenger complains my car is cold they can walk. As soon as my RPMs hit 950 I am gone.

No exceptions.

Within 2 months everything works great never have any problems and average 1 to 1.5 quart oil per oil life monitored oil change.

considering I will be hitting 200000 miles very soon the car still runs and drives like new.

I do the WOOT procedure about once every 3 months and never see any smoke or anything out of the ordinary with my engine.

Hope this helps give some experienced insight

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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I would not replace the engine just because it uses a quart in 800 miles. You are checking the oil level with the engine hot correct? If you're checking it cold and topping it off, you are overfilling it and it will quickly vaporize the excess and burn it through the PCV system.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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You said you are going to continue to WOT.

Its not just WOT, its the procedure that I described above that you MUST do, doing a WOT when you get on the turnpike or expressway is just a maintenance thing, but you MUST do the WOT PROCEDURE

When I asked if you babied your car I was asking it for a reason, you CAN NOT baby this engine and YOURS has been babied because it was owned by an older couple.

A quart every 800 miles is what you get when its babied, start doing the WOT PROCEDURE and you will improve it DO NOT have that engine opened up because of this. Do the procedure

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I would continue the "Italian tuneup"; and pay attention to proper procedure: keeping the tranny in 2nd (because the slowdown, in gear, is just as important as the WOT); exerts pressure to the under side of the piston rings.

Chuck

'25 CT5, '04 Bravada........but still lusting for that '69 Z-28

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Good thread. Having recently acquired my '02 DHS with only 30k miles on it, first thing I did was take it to the dealer for a oil and filter service. I checked the oil have having put about 1000 miles after service and it was 1qt low. I had heard the NS uses more oil than a normal engine but this was ridiculous. I will admit, I have been baby-ing the car. I will do the WOT procedure and see what happens. Anyone who know me knows I'm not the type to baby an engine. <evil grin>

One thing I notice that has me concerned, when cold, the engine has a very noticeable ticking noise. Like a lifter ticking. Goes away after warm up. The dealer put the AC Delco Dexos 5-30 synthetic blend in the car. Is the cold ticking normal for the NS? Could it be the synthetic oil causing it? Or should the noise be investigated further?

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Good thread. Having recently acquired my '02 DHS with only 30k miles on it, first thing I did was take it to the dealer for a oil and filter service. I checked the oil have having put about 1000 miles after service and it was 1qt low. I had heard the NS uses more oil than a normal engine but this was ridiculous. I will admit, I have been baby-ing the car. I will do the WOT procedure and see what happens. Anyone who know me knows I'm not the type to baby an engine. <evil grin>

One thing I notice that has me concerned, when cold, the engine has a very noticeable ticking noise. Like a lifter ticking. Goes away after warm up. The dealer put the AC Delco Dexos 5-30 synthetic blend in the car. Is the cold ticking normal for the NS? Could it be the synthetic oil causing it? Or should the noise be investigated further?

I would use regular old Dino oil a good grade with proper STAR BURST symbols and get the synthetic out, you see the guru state it above in that long thread I posted. I personally have had bad experience with synthetic that causes me to never want to use it. Since oil has been depleted of ZDDP or zinc by our government, there are less wear compounds then when the engine was built and designed, you might supplement your oil changes with a shot of GM EOS. Kevin (KHE) will pop in I am sure to share what he does.

I would use TECHRON in the tank as often as possible (say at each oil change) exactly according to the directions on the container

If you do the WOT procedure you may seat the rings better and blow out any carbon on the dome that might be creating the COLD CARBON KNOCK. As I noted above the 70 to 40 deceleration in 2nd causes negative air pressure in the combustion chamber and BLOWS debris and carbon out, and it further exercises the rings from another perspective.

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thats an odd statement. normal oil consumption is 4000miles/qt. but its normal to see 1000 mile/qt? how can a 4:1 oil consumption increase be considered normal? that almost makes you think keeping track of oil consumption is a waste of time.

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I dont think its NORMAL at 1000 miles, I think its been said its ACCEPTIBLE at 1000 to 1500 I believe 1500 being preferable. Its very important NOT to fill it to the top of the add line on the dip stick, all I did was keep the bulb or tip at the end of the stick wet.

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I had excess oil consumption/leakage on my 94 Deville Concours when I bought it at 64,000 miles. Mine was using/leaking 1qt./1000 miles. I questioned this when the Guru was around. The correct term by GM is that 1qt./1000 miles was ACCEPTABLE. I was furious at first, but after doing some things suggested by the good people on this site the oil use/leakage got a little better. I just kept a quart of oil in the trunk and when the Oil Low message came up I just put it in. When my head bolts finally pulled causing me to buy another caddy and use the 94 for parts it had 167,000 miles. Even with the oil comsumption problem it lasted me over 100,000 miles. My 97 Deville I bought for $4000.00 to replace the 94 had 89,000 miles and no oil consumption between changes. Now at 157,000 miles it only uses 1qt. between changes. I expect this car to go 200,000 to 250,000 miles.

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I dont think its NORMAL at 1000 miles, I think its been said its ACCEPTIBLE at 1000 to 1500 I believe 1500 being preferable. Its very important NOT to fill it to the top of the add line on the dip stick, all I did was keep the bulb or tip at the end of the stick wet.

Can you explain that Mike? I have heard this and I even remember the Guru mentioning it, but he never said why and I cannot for the life of me come up with any logic as to how that could promote excessive oil consumption. Color me baffled.

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When I have my oil changed... it is always right at the "FULL" mark...

I have never had a problem with oil consumption... at least not yet.

It has been over 8000 miles since it was last changed... it is almost a quart low right now...

No oil has been added for the 8000 miles since the last oil change.

It will be changed in the next few days... it says 20% oil life remaining, but the oil is starting to get a little dark.

It is not nice and clear like it was when it was first changed.

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I dont think its NORMAL at 1000 miles, I think its been said its ACCEPTIBLE at 1000 to 1500 I believe 1500 being preferable. Its very important NOT to fill it to the top of the add line on the dip stick, all I did was keep the bulb or tip at the end of the stick wet.

Can you explain that Mike? I have heard this and I even remember the Guru mentioning it, but he never said why and I cannot for the life of me come up with any logic as to how that could promote excessive oil consumption. Color me baffled.

On the previous page where I posted all of the Oil Consumption quotes from the guru, he stated this

The best way to minimize oil consumption in a Northstar is to keep the sumpfilled slightly low (many are continuously overfilled) by only checking the oillevel when hot and only filling the sump with 7 quarts of oil (7.5 with a dryfilter 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 thecrankcase promoting oil consumption

I can only think that overfilling the crankcase could contribute to leaking at the case half. I do recall the guru stating that IF you had a bad case half leak, keeping the oil high or to the FULL line on the stick would promote oil leaking.

I do recall the guru stating that the engine could run on 5 quarts of oil all day as long as there were no high G turns involved. So it is possible for 2 1/2 quarts to be in the crankcase that is over and above needed.

It is possible that some is sucked into the pcv circuit and burned

It is also possible that with the aggressive cross hatch hone on the cylinder walls, the additional 2 1/2 quarts causes oil to be washed up on the piston skirts, it makes its way up to the rings and more oil is actually burned due to the aggressive cross hatch

What do you think?, these are my ideas, but they seem to come from discussions that we have had here

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I can only think that overfilling the crankcase could contribute to leaking at the case half. I do recall the guru stating that IF you had a bad case half leak, keeping the oil high or to the FULL line on the stick would promote oil leaking.

Even a slightly overfilled crankcase would not put the oil level anywhere near the halfcase seam so that doesn't make sense to me.

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

I do remember him saying this, but it makes even less sense to me. He never did explain just HOW this supposedly promotes oil consumption. GM marked the dipstick acceptable range (Min - Max), yet staying within GM's "acceptable" range is "overfilled"? That is contradictory and makes no sense to me.

I do recall the guru stating that the engine could run on 5 quarts of oil all day as long as there were no high G turns involved. So it is possible for 2 1/2 quarts to be in the crankcase that is over and above needed.

I too recall this and it makes perfect sense. In fact I seem to recall him mention that they actually ran it on a dyno with as little as 3 or 4 qts in the sump.

It is possible that some is sucked into the pcv circuit and burned

I have considered this one Mike. Just can't come up with an explanation as to how that could happen by keeping the oil level at the full or max mark.

It is also possible that with the aggressive cross hatch hone on the cylinder walls, the additional 2 1/2 quarts causes oil to be washed up on the piston skirts, it makes its way up to the rings and more oil is actually burned due to the aggressive cross hatch

I agree. The aggressive cross hatch does retain oil and aid in the oil consumption, but that would be the case whether we had 5, 7 or 8 qts in the sump.

I don't know Mike. I've had this discussion before with others and we have not been able to come up with a logical explanation as to why keeping the oil at the top end of GM's acceptable range would promote oil consumption. :shrug:

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It seems reasonable that the more oil in the pan the more oil that would be able to be burned, or that can been splashed upward, maybe there is more turbulance with the added 2 1/2 to 3 quarts, whereas more oil gets up to the rings than with 5 quarts.

I do know that if I used 71/2 quarts my case half leak was worse.

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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You are not the first to tell me that Mike. The guy I had a discussion with about this said the same thing. If he uses more than 7.5 (but not over the Max mark), his consumption goes up, but we could not come up with a logical explanation as to why and he is a pretty knowledgeable gear head. Personally I use 7 myself just for easy measuring.

I cannot imagine what would splash oil upward. I would not think that it could be turbulence because the windage tray should prevent that.

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How about as KHE believes, my oil manifold was leaking and not necessarily my case half, would additional oil overwhelm it in anyway, increasing leaking?. When I over filled it, I smelled oil burning.... and at times would have smoke and smell on hard braking. My engine needed a full overhaul, that is why I didnt undertake the head gasket, it was a big job

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Thanks everybody for the usefull information.....Like I said, I have been doing the WOT for the past 7 months which I got from you guys on this site (much appreciated), at least once a month, when I put on her about 300 miles.....I put her in second gear at about 40 mph and bring her up to about 70-75 mph, 10 times on the highway....She continues to use up a quart every 800 miles when kept about halfway up the dipstick hashmarks...I check the oil hot ( about 10 min. after driving)and keep the oil in about the middle of the dipstick....At about 800 miles the low level oil comes on the DIC and then I add another quart which brings her to about halfway or a little more on the dip stick...Untill the next 800 miles the low level oil will come on and I add a quart....She runs beautifull....I am just going to continue doing the WOT and see if I get better results eventually...Thxs

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