Oil leak

[gthompson6]

I have an oil leak on my 1999 Seville STS that I can't see where it's coming from. I get very little oil on the ground, just quarter size spots here and there, but I am using 1 qt or more every 1,000 miles (maybe less), and can smell a burning oil smell when the car is warm and I come to a stop. I was wondering if any of you experienced Cadillac owners know of, or have had any experience with a product that may prevent or at least lessen this leak (running rotella 10w 30 now). Otherwise this car seems just fine with no real problems. Thanks in advance for all your replies.

[JimD]

One quart of oil per 1,000 miles is not considered excessive oil useage. And yes, these engines do develop external leaks due to the design and the gasket materials available at the time.

Some of the oil consumption can be addressed with regular application of wide open throttle (WOT) therapy. You could "search" the board for recommended WOT techniques.

Oil additives are not recommended (or effective).

[MAC]

Based on the symptoms ("quarter size spots here and there"), it sounds like the oil pan is leaking. But an oil leak could also be a result of the oil filter being loose. If it's the oil filter you should see fresh oil dripping down the filter itself. At any rate, my best guess, based on my own experience, would be that the oil pan is leaking. I would check to see if the pan bolts are loose

This topic has been addressed in the past at CaddyInfo with one suggestion for a fix or to slow down leaking being to remove and clean bolts and block threads with brake cleaner and put some thread lock on each, bearing in mind that it's not difficult to strip the threads in the block by tightening bolts too much. Do not exceed torque specs. which is 9 lb.ft. (according to GM 1994 Service Manual).

[gthompson6]

Based on the symptoms ("quarter size spots here and there"), it sounds like the oil pan is leaking. But an oil leak could also be a result of the oil filter being loose. If it's the oil filter you should see fresh oil dripping down the filter itself. At any rate, my best guess, based on my own experience, would be that the oil pan is leaking. I would check to see if the pan bolts are loose

This topic has been addressed in the past at CaddyInfo with one suggestion for a fix or to slow down leaking being to remove and clean bolts and block threads with brake cleaner and put some thread lock on each, bearing in mind that it's not difficult to strip the threads in the block by tightening bolts too much. Do not exceed torque specs. which is 9 lb.ft. (according to GM 1994 Service Manual).

I had a local mechanic look at it and he seemed to think it was coming from an area around the heads. At first this worried me that it might be the serious head gasket problem that I have read about on this forum, but I have none of the tell tale symptoms, and have put 2,500 miles on the car with no other issues. Plus if it was the oil pan would it really give off a noticable burn smell ? The filter is not loose, I changed the oil myself, and this problem existed before I did that.

[Ranger]

Check the oil pressure switch, oil cooler lines and oil filter adapter "O" ring. I doubt it is the head gaskets. If in fact it is coming from above, more likely a cam cover gasket.

[MAC]

Plus if it was the oil pan would it really give off a noticable burn smell ? The filter is not loose, I changed the oil myself, and this problem existed before I did that.

I don't know the physical makeup of your exhaust system but if its similar to the 1994 Eldorado then it's possible for oil to drip off the oil pan onto the exhaust pipe causing smoke. I've experienced this problem.

[Cadillac Jim]

If you don't get significant spots on the garage floor but you know that it's leaking, then the leak is from pressurized oil, such as the oil filter seal or adapter gasket, the oil pressure switch, or the big O-ring that seals the main bearing cradle. If your engine underside is far wetter than your garage floor, you may have some seepage at the bit O-ring, which is best ignored. If you see a dry oil pan or only spots or streaks, look at the oil filter. I have heard of the cam covers seeping, and torqueing those bolts may solve part or all of your problem.

[BodybyFisher]

You may aleviate some of this leaking by using a high mileage oil, it has seal conditioner in it that might help the seals. I have tried using Rotella 15W45, the engine sounds amazing with it, it has a higher content of ZDDP in it, which is good for our pre-2000 Northstars that have rubbing surface cam lobes (2000 and new have roller cams). Mine is leaking again and i smell smoke but I believe its because where I park to take the train, the ground is inclined and I think its leaking down at the case half as a result, I have tried parking in both directions and it does not help. I need to find level ground. The engine is split down the center of the main journals of the crankshaft (see photo below), there is a bearing half in each half of the engine. Between these halfs are seals, some of the passages are under pressure and there is an oil galley. I believe that my low oil pressure at idle is the result of this case half seal leaking internally under pressure and probably externally (hopefully not under pressure). Here is a photo that I found of the case half that has an ominous look to it, look at were the seal goes. I would love to rebuild one of these engines its a dream of mine..

[BodybyFisher]

Here are some interesting photos

[coolnesss]

Oil additives are not recommended (or effective).

Recently I used some STP oil stop leak in a 66 Chevy 327 engine that had an oil leak - don't remember where it was - and the stuff worked. I usually share the idea that oil stop leak doesn't work, but, the engine was similarly smoking at idle and the smell was bothering me so, I went for it - and it worked. Go figure.

[SIXXDOGG]

I also burn a liter of oil every 1500km or so.....been doing this since I had a new used motor installed 13 months ago......no drips on the ground but my pan is wet under the car.