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1995 GMC Jimmy - Smokes now and then

Its smokes now and then, ussaully when im slowing down then acceleration. Sometimes a little bit sometimes a big puff. Antifreeze is still full after a 40 mile drive. No leaks oil or antifreeze. Trans fluid still good, and on full. But when i got home i have almost a quart quart in a half extra oil. Second time now i drained the extra oil changed filter again. Now im back in the safe zone in the dipstick about 2/3 to full.m i wanna drive it again and see if the oil goes back up again. Help anyone much appreciated. Why am i seeing a increase in oil? I used lucas and 3.5 quarts of 1040 for the oil change. 213000 miles

You’re not seeing an increase in oil. Something else is getting into your crankcase, probably coolant. That typically indicates a bad head gasket.

OP said coolant is still full. I wonder if somehow the oil is being diluted with fuel.

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Depends on how he’s checking it. The reservoir could be full while the cooling system is still low, plus 40 mi. isn’t much of a test. Under the circumstances I’d let it get good and cold and take off the radiator cap. The OP didn’t mention smelling anything unusual, which I’d think would be the case if 1 1/2 quarts of gasoline got mixed in with the oil but it’s entirely possible.