my car is using oil but it is not burning or leaking it. what could be wrong?

Question

I have a 1994 Chevy Corsica with a 3.1 engine, 32,000 miles on it.I check the oil once a week and it is always low. it doesn't appear to be burning it and I don't see that it is leaking it. Anyone have an idea as to what may be wrong ???

Answer 1

Every car burns oil. It is not true if you hear otherwise. Just check your manual. It will, in no uncertain terms, tell you how much oil you should expect to use under different driving condition. In the 1980's there was an outcry regarding the amount of oil the newer cars were losing. At one time GM actually announced that it was not unusual for their cars to burn as much as one quart per 1,000 miles!!! Most of the time the oil your car burns can not be seen coming out of the tailpipe, which I believe is how you try to determine whether or not it's burning oil.
Now. I don't know how much oil you are losing. If it is not leaking, you are burning it. Even if you had a bad head gasket and the oil was getting into your cooling system, you would know it. The cooling system is "closed" and any large amount of additional fluid would overflow the system and eventually leak from the over flow tube. If you are losing about one quart every 2,000 miles or so I would bet you don't have a major issue. If you are losing a quart every 300 miles, then you are most certainly burning it. Check what comes out your tailpipe in the morning. It may be smoking then, in which case you have bad valve seals. Bad rings will cause premature oil consumption as well. PCV valve failure will also cause oil to be passed by the rings to the combustion chamber and burned as fuel (but rings are unlikely if only at the 32,000 mark). Any excess, unburned oil will either be cooked of by the catalytic converter, or start to clog it! Bad news! Again, not knowing how many miles you drive in a week, I can not specifically diagnose your problem. But, I am not alarmed as yet. As long as the car is not exhibiting any driveabilty problems. I would not worry much if I were you.

Answer 2

I am wondering how good your cousin was at changing the oil in the car while he owned it. If you are consuming 3 quarts of oil every 700 miles and you aren't leaking it out somewhere then I would say the engine is worn out. But here are a couple of suggestions. First thing I would do is replace the engine PCV valve. If it is stuck it could be causing the oil to be burned because there is pressure in the engine that is not being relieved. Next, I would change the oil again and replace it with 20-50 weight oil unless you live in Canada or some other really cold place. The heavier oil will stay in the engine longer if it is a case of bad piston rings (which is what I am suspecting). I would add a quart of Marvel Mystery oil after 200 miles and let that mix with the oil in the engine and see if it will clean things up (it is possible that the engine piston rings are stuck from such little use as 66K miles in 13 years). Check the oil every 200 miles. If nothing else works you might try some engine restoration product like STP makes, but really all that does is thicken the oil to try to keep it in the engine longer, running 20-50 should do the same thing. I would have a mechanic check the compression in the engine. If you find that it is very low (like <100PSI) you really need to rebuild the engine or just run it like it is and keep replacing the oil...

Answer 3

What Stu said.

You didn't say how much oil you're going through. It it's something like a quart a month, your engine can leak that much very slowly without making puddles of oil under the car. Most small oil leaks that are gasket related don't really start oozing oil until the engine gets up to operating temp, and then the leak simply burns off on the block or exhaust manifolds. This is usually not too hard to find since it looks like a dirty gooey thick congealed mess around and below the leaky area. Although seeing any part of the block below the intake in the engine compartment of cars made in the last 20 years can be a challenge.

If you are absolutely sure you aren't leaking or burning oil, you need to check the coolant. And when I say check the coolant, I don't mean at the overflow tank. You need to pop off the radiator cap, WHEN COOL, and stick your finger in there. If it comes out looking clear and green, then it's OK. If it's at all creamy looking, then you know where that oil's going. You're going to need a mechanic if that's the case.

Answer 4

Car Using Oil

Answer 5

How do you know its not burning it. The catalytic converter will burn off any smoke from oil burning.
Your 3.1 GM v6 is famous for having intake manifold coolant leaks. Check your oil for discoloration from coolant. It will look like coffee with cream in it.

Answer 6

the piston rings may have a little wear on them, allowing a small amount of oil to slid by, and get burned in the compustion cycle. this is not unusual. check the tail pipe when first starting the car to see any black smoke. also at a high rpm.

Answer 7

In addition to the excellent responses above, another possibility is a clogged pcv valve. This can cause oil to seep out of the car only when the engine is on.

In case anyone is interested, pcv functiones to vent out crankcase pressure that may be present due to blow-by gas around the piston rings. if this pressure is not allowed to vent out properly, the pressure can cause oil to seep out around gaskets and sometimes the oil dipstick to pop out.

Answer 8

What does your coolant look like? The oil is going somewhere. If it is not being burned, not dripping out, it must be going in the coolant.

Answer 9

if its not burning it and its not leaking,then theres only 1 thing left and thats it going in the water,better check the head gasket.

Answer 10

I agree with Stallion. That oil is going somewhere, check your coolant levels. There should be an overflow tank, if it ain't clear or green, you have found your oil.