oil level

[lost1]

I just bought a 99 STS about two months ago and it has been using alot of oil. I just started doing the WOT's to see if that will help. but at what oil level is it safe to run in the northstar.

[Ranger]

The reason for the 7.5 qt capacity is that the engine was built as a high performance engine. 7.5 qts, ensures that the sump will not run dry with a 1g lateral force at WOT. That said, they ran it at the factory with as little as 3-4 qts during testing. While I would not run it that low, it is perfectly safe wait til you get the Check Oil Level message, which comes on at 2 qts. low unless you plan on taking on ramps at WOT.

[winterset]

Only check the oil when hot. otherwise, you will overfill, and the extra will blow into your intake, and next time you check cold, you will incorrectly read low, then you will unknowingly overfill, and so and so on. on a warm engine, let it sit a few minutes, then check.

[Ranger]

Technically, checking it hot is correct. That said, I got curioous about this and checked it hot and cold. The difference is about 1/8" - 1/4" on the dip stick. Not enough for me to be concerned about.

[lost1]

Thank you. I was worried that this using oil thing was going to get the best of me and i was going to blow something up. this car already has 127000 miles on it and I would like to get at least 200000 on it. I do believe that i need to get into a habit of checking the oil once a week instead of when the check oil light comes on. i just filled it up to 7.5 Q and hit the trip meter i want to get a good estimate on how much oil it is using.

[JohnnyG]

JohnnyG here, Welcome to the board! (At least I have never noticed a post from you before. ) I'm the one and only, SELF PROCLAIMED, expert on this subject!!!! But I would give that all up for one post from bbobynski.

I have run my '99 at the add mark from the time I was a little kid on this board, about 3 years ago. I'm 57 years old now, and have never regretted the decision. At the ADD mark, the engine still has about 5-6 quarts of oil in it, run it until the "add oil" or "check oil level" light comes on (I have never seen either one) and never look back. Keep up the WOT's, but don't overdo them. An ON ramp here and there, a good 2nd gear blast once in a while, maybe a trip to Florida once a year, will be plenty. That engine will last until 300,000 miles!

More importantly, if you have no PROOF that it has been done yet, change the coolant, and add the correct amount of sealant to the LOWER radiator hose ONLY.

I love my '99! The MOST erginomically correct cruise control of ANY car! 26.5 mpg highway on regular gas. By all means add the shock tower brace as soon as you can for about $30.00 US, and live long and prosper!

winterset, I'm with you on the check oil HOT thing, but what's that about an intake??? If the oil goes into the engine via the PCV valve, it's burned and gone. Yes, the residue sticks the rings, and an excessive amount is burned....but that "next time you check it" thing has me puzzled.

[BodybyFisher]

WOT's are good for basic carbon maintenance, but try this procedure:

Get on open highway, start at 40 MPH, put tranny in second, 3/4 throttle to 60 then full throttle to 70, take foot off gas and let tranny pull the car down to 40, repeat 10 times... This will exercise the rings, loosen them, and blow out carbon on deceleration as vacuum is created.

I do it once a week. This should decrease your oil consumption.

I wouldn't do it in extremely hot weather however, even though I am sure it would be fine.

[lost1]

I do have another question. the guy i bought this car off of only ran synthetic oil in it. with what i have read, i should go back to conventional oil to reduce oil consumption. but everyone i have talked to around here tells me that once you run syn. if you switch back to con. you could cause problems. is that just a myth or is there some truth to it?

by the way, i got up to 106 today and i was doing WOT's....oops

[GreenMachine]

you can go back to conventional from synthetic (or the other way around) with no problems, thats one of them myths that crop up.

[BodybyFisher]

Agreed, changing back to conv oil would not be a problem. I would do that immediately, and consider using the high mileage blends that are out there. To me I think the synthetics are effectively less than the stated viscosity and tend to leak and be consumed more.

Your car did not come from the factory with synthetic. Many think that its better (some because they spend more), but unless you are racing, towing or driving a taxi AND the engine can handle synthetics, I would stay with standard oil. PLUS, with your oil consumption it MUST be expensive to keep adding oil with synthetic.

Try the procedure I outlined above and read the following that I believe was posted by the NS guru:

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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.

An 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.

[JasonA]

Some of the synthetic oils (like Mobil 1 especially) are forumated quite thin. Keep in mind that each viscosity has a range. Mobil's 5W-30 is actually closer to a 5W-20. Their 0W-40 is actually pretty close to a 30W when warmed up.

However, some are the other way around. For example, the Castrol 0W-30 (known as "German Castrol") is actually thick for its weight, closer to a 40W.

I'll say that most of us use conventional oil, with fantastic results, myself included.

[winterset]

I understand & agree that it will be burned. Just that it leaves a gummy residue on the throttlebody. it can lead things there to stick if done over a long period of time. Been there done that. I don't top off anymore, and I have noticed a difference.

[BodybyFisher]

I understand & agree that it will be burned. Just that it leaves a gummy residue on the throttlebody. it can lead things there to stick if done over a long period of time. Been there done that. I don't top off anymore, and I have noticed a difference.

I was wondering where that gummy stuff comes from on the back of the throttle plate

[JimD]

Not to swerve this too far off topic. The following words are from you-know-who:

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"The gunk or coke that forms on the backside of the throttle blades

and in the perimeter of the throttle body bore has several origins.

You are corect in that the throttle blade is in clean air and well

upstream of any combustion. Unfortunately, several substances other

than fresh air get induced into the intake manifold. PCV gases

(combustion blowby, byproducts of combustion, moisture, light ends

of the oil, and some atomized oil) are pulled from the crankcase to

keep the crankcase clean and the PCV gases are circulated to the

intake to be pulled into the combustion chamber and burned to

eliminate the pollutants. EGR is introduced into the intake manifold

to control the formation of NOx (pollutant) and to improve the

engine efficiency (yes, EGR causes better fuel economy). EGR is

exhaust gas...which is inert (good thing) but it contains soot (bad

thing). In addition, at shutdown, any liquid fuel or fuel vapors

from the fuel injectors is trapped in the intake plenum under the

throttle blades.

Several things happen.

One, any oily deposits from the PCV tends to trap the soot in the

EGR and cause it to stick to the inside of the intake manifold

plenum. Seems to stick to the bore of the throttle body and the

blade most often .... hmmmm...wonder why?

There is a good reason. The throttle blade is the coolest

(literally) part of the induction system as cool air is always

flowing over it. At shutdown, the manifold/throttle body/etc. tends

to cool down with time. As it cools the temperature gradually passes

thru the "dew point" of the various gases and components in the

manifold. As the dew point is reached, the particular component

tends to condense on whatever surface is coolest. Guess what it

usually the coolest...the throttle body and the blade. So, over

time, all the gunk that is in the maniofold in very small quantities

at any given instant slowly accumulates on the throttle body. And

gets baked or coked the next time the engine is started or run and

heated up. Repeat cycle thousands of times and it is time to clean

the throttle body."

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[BodybyFisher]

Ahh, I feel comfortable now.... I miss that masked man

[epricedright]

He never ceases to amaze me!

[JohnnyG]

So overfilling does have an effect on intake and throttle body cleanliness, but no effect on oil levels. The oil can't just sit there in the intake and eventually drip back down into the pan. Thanks for clearing that up!

[JIMDTS]

For what it's worth most of the time esp in the year you have all the WOT's in the world are not going to fix the oil usage it's the rings I have an 01 deville after the new rings and pistons high oil usage gone I use about 1qt every 3k now prior to that 2qts every 1200 miles

Good Luck

Jim

[CaddySTS]

Well, for what is worth, I experienced the decrease of oil consumption when I switched to conventional oil. When I used Synthetic, my consumption was around 1q per 1,000 miles, now it's no more than 1q per 2,000.

I do WOT once a week, but I am doing it differently. I would keep it in D, and do around 40mph on a highway, then hit it hard, the car will shift it to 2 on it's own and only then I would manually set the shifter to 2 while accelerating. I would keep accelerating to 60-65, then take off and let the engine slows the car to about 40, then repeat it (3-4 more time) now keeping the shifter in 2 all the time. I just do not like to manually shift the car. I would let the engine do it for me first.