Do you mind if I smoke?
You're stopped at a light. The car in front of you has smoke coming out their tailpipe. Worse: you're looking to buy a used car, and smoke comes out of that tailpipe. Or even worse: smoke starts coming out of your tailpipe. What does it mean? Exhause smoke can be black, blue, or white/gray-ish. It means something is wrong with the engine. Black smoke means that the engine is burning too much oil. It can be simply that the air filter is clogged. Just change the air filter. If you go to change the filter, and it's soaked with oil, then that's a problem. Other causes of Black smoke are faulty fuel injectors, a bad oxygen sensor, or a blocked intake manifold. Blue smoke indicates that the engine is burning too much oil. This can be caused by worn engine componets: bad valve seals, bad piston rings or a bad PCV valve. Blue smoke can also be due to too much oil in the engine. This can be the result of an owner misreading the dip stick and putting too much oil in, or from goin...