How Do You Determine Source of Oil Leak?

[clevo]

The car is a 1995 cutlass with 65,000 miles on it.

It began leaking oil a few months ago, but I cannot tell where it is coming from, and was hoping my limited description of the problem will ring a bell with someone.

The driveway has oil spots on it where they car is parked. I can see that the bottom of the oil pan is soaked with oil, and so is some of the framing in the same area, but I cannot trace it back to any one point.

Also, when I am stopped at a light and am running the heating/AC fan, there is the faint smell of burning oil coming in the car.

I was planning on switching this car over to synthetic oil, and in preparation for total use of sythetic used 2 quarts of Mobil 1 as part of my last oil change. The leak started shortly after that. Did I cause my own problem?

The Mobil website says synthetics do not cause leaks, but I've since seen a couple of posts that state the stronger detergents in sythetics can clean to the point of removing dirt that is sealing a potential leak.

Any advice on where to look would be appreciated.


KC

[RacerX11]

You can get dye to put in the oil that will show up with a flourescent light. You then run the engine after dark with a light and look for the leak.

Marty

[dohcfiend]

DUDE that is awesome. i didn't know that. to find usually i try to trace it to the highest point and go from there. if it is a small leak it can be hard to find sometimes.

[TheProfessor]

try the timing cover or the main seal
if you cant see it leaking from the top then its probaly down there somewhere

[SappySE107]

I have switched between the 2 many times, but never mixed like that. It can't be any worse than synthetic blends.

I would check under the lower intake first. If that O ring on the distributor location is shot, you will have quite the oil leak. If it is that, you have a few options for taking care of it, easy to hard.

I usually just clean all the oil off with brake parts cleaner and some rags, then run the car and see if it leaks just sititng there. If not, drive it around for a bit and then check it out. The dye would probably be faster if its not that O ring or something easier to see.

[blk92z34getrag]

Synthetic oil has detergents in it that can kill really old gaskets.

I ran synthetics once a long time ago and right after I did that my main seal started leaking about 1qt. every 1,000mi. I don't run synthetics anymore, not untill I do a full rebuild at least.

I've heard that switching at high mileages can cause oil leaks because they cause the gaskets to get birttle? Or something... can't think of what it does to them, but I know it causes them to leak.

[TheProfessor]

well the synthetic oils are a finer grade
so they would leak out a apot that regular ooil wouldnt
they also have valvoline maxlife synthetic now

[clevo]

I suppose I could always go back to 100% non-synthetic oil and hope that "cures" the problem. Or has the "damage" been done and switching back will not solve anything?

I didn't think synthetic would be a problem for this engine based on what I read on mobil1.com. (relevant text is quoted below) And I only put in 2 quarts of synthetic! Of course, they are trying to sell the stuff, so I suppose I should have been more skeptical when I read this.

http://www.mobil1.com/index.jsp

MYTH: Mobil 1 will leak out of the seals of older cars.
Mobil 1 does not cause leaks. In fact, new Mobil 1 with SuperSyn? was tested in dozens of industry standard and OEM tests to prove its seal performance. It is fully compatible with the elastomeric materials from which all automotive seals and gaskets are made.

ExxonMobil engineers are wary of conventional oils that tout their use of additional seal-swelling agents. With extended use, these agents can over-soften engine seals, resulting in leaks. More to the point, an oil additive will not rejuvenate worn or damaged seals. The damaged seal may have been caused by a worn rotating metal component in the engine.

If an older engine is in good condition and does not have oil leaks, Mobil 1 with SuperSyn? provides the same advantages as when used in a new engine. ExxonMobil recommends taking measures to repair the leaks, then using Mobil 1 with SuperSyn?. ExxonMobil also always recommends following the automobile manufacturer's manual for the proper oil to use.

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