1991 Volvo 240 Question: Excessive smoke comming from tailpipe.

Upper radiator hose, and oil pan gasket could have something to do with the smoke coming from the exhaust. If you are driving with low or no coolent and engine oil, you are doing damage to your engine every time you start it. or if the levels are being kept full and leaking on your exhaust system and the smoke is caused by burning off the exhaust and blowing out from under the car. If you have these problems you need to get them fixed but if the smoke is coming from inside the tail pipe you already have other more serious issues.

And if your son put too much oil into the engine, the rings could be blowing oil through.. first things first.. what color is the smoke? Blue ish., oil, white and sweet smelling, antifreeze (head gasket), black- bad timing or bad ignition...