A STRANGE OIL PROBLEM

[ROBHWAL]

I own a 2001 SLS with 52000 miles. About a year or so ago it started using a quart of oil every 400 to 500 miles. It was still under warranty and the cadillac dealer claimed that they decarboned the engine.That did no good.I have tried the WOT many times and that does not help.

I am now taking it to a mechanic who used to work for cadillac. He changed the oil,filter and all of the rubber hoses going to the PCV valve.HE put in 10w-40w oil, which helped a little. The oil consumption is now about 600 miles per quart.Tha car does not smoke when started or while driving.

The main problem is that there is no oil on the top or bottom of the engine,but the insulation under the hood is saturated with OIL. Has anybody else had this problem?

[BodybyFisher]

We have not heard of the padding getting saturated with oil, you need to find out where that is comimg from. Get rid of the 10W40 in your car, especially in cold weather. Fix the problem 10W40 is a bandaid

WOTs are NOT enough to fix your oil consumption, have you done the WOT Procedure?

[Texas Jim]

This trouble shooting step probably sounds goofy... but the problem sounds goofy also.

If I read it eight...Insulation blanket is oil soaked and no oil is on top of the engine.

I might go get a LARGE sheet of paper and tape it to the bottom of the hood...then when the hood was closed...it would be covering the engine.

Drive it a short distance and see where the oil is on the paper.

Directly BELOW THAT is where the oil is coming from that is soaking the insulation.

[Cadillac Jim]

Sometimes a Northstar that has been babied consistently for a long time can get stuck rings and that will cause oil burning. The GM de-carbonizing treatment for the Northstar is similar to their process for un-sticking rings but it is NOT the same, and decarboning will NOT unstick the rings.

Cadillac service bulletin 01-06-01-011 deals with oil burning on 1996-'99 Northstar V8s. There is a later one; Ranger or BodybyFisher will likely have the newer one. The cure, says Cadillac, is to do a ring cleaning procedure (seems those long oil change intervals weren't such a good idea after all). Cadillac recommends using GM cleaning kit (P/N 12378545, probably updated by now) and Kent-Moore J-45076 induction/evacuation tool to do the job. The cleaner is added into the cylinders through the spark plug holes and allowed to soak the rings for two hours [see below]. The cleaner and dissolved crud is then vacuumed out of the cylinders through the spark plug holes, followed by an oil change. Cleaning the throttle body and EGR valve is also recommended.

In the later versions of the Cadillac service bulletin they warn not to leave the solution in the cylinders too long. The bulletin says that if it is left in the cylinders longer than three hours, the gunk will settle back down in the rings and the car will be worse off than before. When I had mine done, the tech didn't read the bulletin and left the solvent in the cylinders for 4.5 hours.

[BodybyFisher]

Yes, but the WOT Procedure can do that same thing. If he is just doing WOTs, that is not enough

[Ranger]

I don't think this has anything at all to do with extended oil change intervals. I change mine at 10K and am still at 25% and have no problems.

I'd try Tex's idea. That much external leakage should be pretty easy to spot.

[JohnnyG]

is to do a ring cleaning procedure (seems those long oil change intervals weren't such a good idea after all).

Excessive oil usage has absolutely NOTHING to do with extended oil changes. Engine design of the year NS engines that you mention had the top rings EXTREMELY close to the flame front of combustion. This reduced emmisions and increased HP by promoting an extremely hot and complete burning of fuel. Unfortunately the viscosity index improvers of the time were not up the job, and broke down in that heat. It made absolutely no difference if the oil was new, or 5000 miles old, the VII's would burn and cake on the top rings, then the next...etc. End result, carbon coated and stuck rings.

Solution, regular hard driving, an occasional WOT, and a ring decarb if you are lucky enough to find somebody that will do it, and do it correctly.

[Ranger]

Johnny, do you know when they changed those pistons. Maybe we really don't need WOT that much anymore.

[dgaouette]

At this point I've owned eight NS and oil consumption has never been cured on the earlier ones. I always drive hard, WOT regularly and still they suck oil. My 03 Seville never uses a drop between oil changes but my 99 Eldo and Concorse suck a quart every 700 miles. I bought the concorse with almost 20K on it so I don't know the history prior to my purchase but the eldo was new and it always drank oil. I always ran Mobile one in that one as my 97 seville drank and I was told that the oil could not hold up to the higher temps causing ring sticking. That's way I decided to give mobile one a shot. One thing I will say is none of my cars ever got worse and when I did the infamous timesert job on my 97, the cylinder walls were absolutely perfect, obviously well lubricated at 122K+. The oil rings were all stuck but the top two were clean and free, thus good compression.

[Cadillac Jim]

I always have asked for synthetic and I have a lead foot. Up until about 80,000 miles my car never burned oil so that I noticed. I suspected that I was not being given synthetic oil for a few months, and within two oil changes it went from no noticeable oil burning to a quart every 500 miles. I noticed that after a "change" (keep reading) and I would get the "Check Engine Oil" message and put in two quarts of Mobil 1, oil consumption would decrease and the engine would smooth out noticeably, which told me that whatever was in there it wasn't fresh Mobil 1. The same mechanic let the ring clearing solution sit 4.5 hours in this engine. The next oil change I caught him cold dead to rights skipping the oil change and changed mechanics. With real Mobil 1 5W-30 the oil consumption decreased to about a quart ever 1200 miles over the next few months. That's where it sat for a couple of years until I had a head gasket problem. This was at 116,500 miles and I had significant O-ring seepage, so between these and an occasional blinking oil light at idle I figured fixing it all was a push with a remanufactured engine so I got an exchange engine; I'm past the age for heavy-duty DIY and don't have room for a project car, and I needed my Cadillac every day. Not too much later the FPR died. The cat was partly clogged; I was rear-ended by a teenager on a cell phone that took out my exhaust system and I ended up with Borla XS straight-through mufflers and I could then hear it restricting. I got a new cat and thought everything was OK, even though I noticed a slight "improvement" in torque with a dead spot at redline, which I wrote off to the distance from the exhaust flange to the new cat cavity. Eventually I got a cat efficiency code and it turned out that my new cat had a crack. I replaced it and my engine torque curve is now exactly the same as the original engine.

But, I digress. With synthetic oil and a lead foot, I got mine from a quart every 500 miles to a quart every 1200+ miles, and wasn't adding oil between 3,000 mile oil changes. If that doesn't work for you then get the GM ring unsticking treatment, but make sure that you have someone who can do it right. If you have it going 1,000 miles or more to a quart of oil, you have a better chance with the GM treatment. If you take it in burning a quart every 500 miles, ask the mechanic to consider doubling up the solvent -- leave it in two hours, suck it out and put fresh in, and leave that another two hours, then complete the treatment. I suggest that you get a copy of the current TSB on the ring unsticking job and have it in your hand when you take the car in.

That's the in-car fix. If I had a 1995-1999 Northstar and I had a high-mileage engine out for any reason, I would perform these repairs:

• Timeserts on the head bolts and new head gaskets from GM or top-tier OEM equivalent design for aluminum-to-aluminum seal.
• Clean, inspect, and replace everything in the EGR system as appropriate.
• New case-half O-ring.
• New oil sending unit and any other repairs that looked like a good idea on the oil filter adapter; watch for ham-fisted cross-threads and wrench damage to the oil sending unit.
• New water pump and belt; inspect the idler and replace if necessary.
• New serpentine belt and any fixes on idler and pulleys that looked like a good diea.
• New metal heater hoses behind the engine.
• Check and replace motor mounts and torque wishbones at will; a loose one can let the engine beat up the metal heater hoses...
• New spark plugs and wires, GM OEM, and check the ignition modules with an ohmmeter.
• Shine a light in the exhaust flange and inspect the catalytic converter. Contrary to reputation, they are cheap -- about $100 installed -- and they can become partly clogged by coolant or excessive oil burning.
• Check, inspect and replace oxygen sensors at will, particularly the one that is hard to reach with the engine installed (Bank 2, Sensor 1).
• If you have a blinking oil light and the oil pressure sending unit looks good, pull the damper and front cover and give it a new oil pump.
• Check and replace the timing chain tensioners as appropriate for at least another 100,000 miles; Northstar teardowns are pretty infrequent.
• Check the cams for wear. If you replace a cam, replace all of them and the lifters.
• How's the transmission?

But, that's just me. Oh, does anyone know about a heads-off treatment for stuck rings?

[JohnnyG]

Johnny, do you know when they changed those pistons. Maybe we really don't need WOT that much anymore.

The change would have come in the 2000 m/y production which is also when the NS was rated for regular 87 oct. BTW.

The rest of the posts (below mine) make perfect sense. On the older engines, (pre 2000) synthetic oil was not normally recommended, and in certain engines could increase oil consumption significantly through various avenues. It could be increased seal seepage, case half leaks due to porous blocks (VERY different from the case half seal leak which BBF corrected me on before), or just excessively aggressive cross hatch pattern of the cylinder walls (new stones in the hone, the guru once said). In the interest of low COST PER MILE, which was always a big GM consideration, synthetic was not required and the engine was not designed to need its high temp resistance.

HOWEVER, the use of synthetics did provide one additional benefit, and that was the minimal use of VII's (some did not use any at all). These were the biggest culprit in the stuck ring issue. Synthetics didn't need as much of them to stay in grade. Therefore it follows that those that DID use synthetics in older engines, when other factors do not contribute to oil usage, could effectively REDUCE oil consumption due to fewer stuck oil rings.

I'm not saying here that newer engine owners need to abandon the WOT altogether, but a "lead foot" is still helpful. These are high performance engines, and can't stand to be babied all the time.

[Texas Jim]

I'm not saying here that newer engine owners need to abandon the WOT altogether, but a "lead foot" is still helpful. These are high performance engines, and can't stand to be babied all the time.

Good... that means that I am driving mine right.

Oh, btw... mine uses almost -0- oil...maybe half a quart in 5000 to 7000 miles.

[Texas Jim]

Maybe we really don't need WOT that much anymore.

Ranger,

DON'T SAY THAT...

I love the sound of the 4 cams and 32 valves as it winds up.

[Ranger]

Note the word "need". You can always give her hell just for kicks.

My front mount is bad (again ) so I'm taking it easy on her until I get the new improved one from Jake and have it installed before the warranty runs out in May.

[winterset]

Are you overfilling the crankcase? - remember to check oil level on a warm engine. is your PCV valve ok?

[BodybyFisher]

I did the WOT Procedure last night on the Long Island Expressway.

Here is the procedure

Engine fully warmed up

Oil up to some place on the stick (just the tip is ok)

Slow to 40, put tranny selector in 2nd gear

Floor the gas pedal and take the RPM up to 5800 JUST BEFORE THE PCM FORCES the SHIFT on the 275 HP engine

DO NOT allow the PCM force the shift from 2nd to 3rd because you will not get the important high vacuum deceleration

Once you hit about 5800 or 5700 RPM you will be doing about 75 or so, let your foot off the gas and let the tranny slow you down to about 40.

Repeat this 10 times put the car in OD and drive home.

I did this last night and for the first time I used FULL THROTTLE and hit the PCMs automatic UPSHIFT at about 5800, I was in third, and the deceleration was not too strong, I did not let that happen again.

The deceleration exercises the rings and loosens carbon, the deceleration also causes high vacuum that SUCKS that carbon OUT of the combustion chamber.

I do this monthly and usually right after an oil change. I love the sound of this engine at 5800 RPM.

[ROBHWAL]

Thanks for the replys. I was going to take it back to my mechanic tomorrow but we are getting snowed on here in OHIO like crazy,so i cancelled until next week. He wants to put dye in the oil and drive it for a while and then check it with a UV light for leaks.

I have been doing the WOT procedure, but not 10 times in a row.Maybe that is part of the problem.

[BodybyFisher]

Thanks for the replys. I was going to take it back to my mechanic tomorrow but we are getting snowed on here in OHIO like crazy,so i cancelled until next week. He wants to put dye in the oil and drive it for a while and then check it with a UV light for leaks.

I have been doing the WOT procedure, but not 10 times in a row.Maybe that is part of the problem.

Where did you learn the procedure on this board, did you do it in second gear with deceleration like I described above?

[Ranger]

DO NOT allow the PCM force the shift from 2nd to 3rd because you will not get the important high vacuum deceleration

Sure you will Mike. If the selector is in 2nd, unless I am wrong, I believe it will down shift on deceleration

[BodybyFisher]

DO NOT allow the PCM force the shift from 2nd to 3rd because you will not get the important high vacuum deceleration

Sure you will Mike. If the selector is in 2nd, unless I am wrong, I believe it will down shift on deceleration

OK let me explain.

You are in 2 on the selector

You go beyond 5800 rpm and the PCM forces an upshift to 3rd to save the engine from going above the red line

When you take your foot off the pedal at that point the deceleration is NOT as strong as it would be if the tranny was actually in second gear before the PCM did it magic

So dont let the PCM put you into 3rd because in 2nd you get stronger deceleration from the tranny causing the high vacuum

Do you understand what I am saying Ranger? Stronger decel from 2nd than a forced third.

Yes it does DROP back to second when you get down to about 40 or so while in second I felt it last night

I recall the GURU saying stop accelerating before the forced upshift and last night I saw why. Try it yourself.

[JohnnyG]

Yeah, you really want to stay in second on the decel part, like from about 75 or so as I recall.

My '08 hasn't needed the WOT yet, and probably never will, but more on that later. Let's just say it has had an excursion above 5000 rpm in second for now, just to get the rings seated well. It hasn't used a drop of oil yet.

I never did the WOT 10 times in a row either, on my '99 STS that is. It just seemed a bit too hard on the tranny for me. Then again, I never realized complete cessation of oil consumption either. I DID manage to reduce it to levels that I could live with.

Oil usage on that engine was wierd too! I would use about 4 to 6 ounces of oil on a 300 mile trip, AND I would use 4 to 6 ounces of oil on a 1000 mile trip! I never did figure that one out!

[BodybyFisher]

I agree Johnny, I used to think the same thing, maybe now that I have 122K I am less protective. I think the first few times going ten times would be a good thing then less thereafter. But I do understand your apprehension.

As a matter of fact, last night was the first time I did it ten times and the first time the PCM ever upshifted into third, prior to that I had heard that the PCM would do that but never experienced it.

I did it because I am getting a cold rap that goes away when it it warmed up, do I said, the heck with it, let me run the heck out of it the way the GURU recommended. I will say this, it was much quieter just now when I took it out, but its 40 degrees, so I am not sure...

By the way, the present you sent me is fantastic, THANKS AGAIN....

[Ranger]

Do you understand what I am saying Ranger? Stronger decel from 2nd than a forced third.

Yeah, I understand that part.

Yes it does DROP back to second when you get down to about 40 or so while in second I felt it last night

That's the part I was not sure of. I thought it would be higher.

Yeah, you really want to stay in second on the decel part, like from about 75 or so as I recall.

I think I've gotten to 80 and it was still in 2nd. Nice hard decel.

[BodybyFisher]

You might have with a 300 HP engine the RED LINE is higher than 5800, what is it?, unless my 275 HP is lower than 5800, not sure. I was about 75 when it shifted into third and I quickly saw 5800, but it could have been 5600 - 5700 also. The 300 HP engine would shift into 3rd higher due to the higher red line

Imagine? 75 in second gear, I LOVE that sound....

[Texas Jim]

You might have with a 300 HP engine the RED LINE is higher than 5800, what is it?, unless my 275 HP is lower than 5800, not sure. I was about 75 when it shifted into third and I quickly saw 5800, but it could have been 5600 - 5700 also. The 300 HP engine would shift into 3rd higher due to the higher red line

Imagine? 75 in second gear, I LOVE that sound....

Mine shifts at 6800 RPM, instead of 5800.

It shifts from 2nd to 3rd at 80mph and I have the 3.73 gearing instead of 3.23.

I wonder what speed it would shift at with the 3.23? Probably close to 100.

I too love that sound.

Ain't nothing like 4 cams and 32 valves at 6800 RPM.