Blue smoke coming from the exhaust indicates that oil is somehow entering the engine cylinders and burning off. This burning of oil in the cylinders will cause the smoke from the exhaust to look blue. There are many seals and gaskets in the engine that protect against leaking oil into the cylinders. A sudden onset of blue smoke from the engine exhaust means your vehicle needs servicing as soon as possible. If your engine is high mileage and there is a lot of blue smoke coming from the exhaust, it may just be a sign that the engine is old and is in need of an overhaul. Heavier weight oil may slow down oil leakage into the cylinders and help stop the blue smoke coming from the exhaust pipe.