Exhaust: Troubleshoot Smoke Colors
White smoke can indicate that you are burning antifreeze. This can signal that you have blown a head gasket and that antifreeze is making it into the combustion chamber and blowing through the exhaust.
Black smoke is usually unburned fuel and can generally be associated with running rich. A very common association with black smoke is a boost leak which is also associated with poor fuel economy, and fuel cut
Exhaust smoke that is "bluish" in color usually signifies that oil is getting into the combustion chamber or exhaust and burning off. This condition is usually refered to as Burning Oil.