Hey guys, I’ve got smoke coming out of my oil dipstick tube. 1996 Mercury Mystique 2.0L automatic, 62000 miles. I noticed a burning oil smell after a short (10 mile) drive, and checked the oil when I got home. A few wisps of smoke smelling of burning oil came out of the dipstick tube when I removed the stick. I was just curious how worried I should be about this. As far as I can tell, my cooling system works (radiator hoses are warm, good hot air from the vents, thermostat and coolant recently replaced, hoses inspected, no leaks) and I’m not thinking the burnt oil is caused by overheating. There hasn’t been any noticeable oil consumption, and I’m pretty diligent about checking the oil on this old car. Oil changes every 3000 miles since I’ve owned the car; dealer performed scheduled maintenance for the old owners.
Here’s my thinking: a worn piston ring allowing oil to be burnt and then sucked back through into the crankcase. When I changed my spark plugs, I did notice an oily residue on one of the plugs (cylinder #1), which also leads me towards a piston ring diagnosis (though I was hoping it was a valve seal causing the oily spark plug, or even a spark plug seal). Do you guys think a wet compression test is in order, or should I go ahead and get a leakdown test? I am going to buy a compression tester, but I do not have an air compressor to use with the leakdown tester; I’d have to take it to a shop.
I do need to service the PCV system (and would have done it today, but the parts hadn’t arrived at the store) – would a PCV problem cause the oil to burn, though?
If you guys aren’t thinking piston ring, I would love to hear any other suggestions you may have, and any comments on the urgency of getting it looked at by a real mechanic. Thanks in advance from this novice (but I’m learning a lot from you guys!).
edit: new theory, after doing some more productive homework: My PCV system is messed up and the blowby is normal; it just isn’t getting cleaned out effectively. This allows me to maintain some hope of not having to hire a machine shop, so it’s my preferred theory at the moment. Still going to get that compression tester.