Why does exhaust smoke come out different colors

            Unusual smoke coming from your car's tailpipe is not a good thing, and different colors of smoke depict a different problem.

White or gray smoke: White smoke indicates coolant is being burned along with the fuel and there is a leak somewhere in the engine block, cylinder head and head gasket.

Blue smoke: Blue smoke indicates leaking valve seals or guides or worn piston rings, which allows engine oil to seep into the combustion chamber, causing the oil to burn with the fuel. Hence it produces blue smoke

Black smoke: Excessive fuel is burned in the combustion chambers due to a leak in the fuel injector, a stuck fuel pressure regulator, or a restriction in the fuel combustion tube. This usually happens in relatively old cars and in such situations, it is very important to have the leaks checked by a specialist mechanic.