eli5 – Why do old cars have more visible smoke coming out of their exhausts?

Question

Where is that smoke coming from? Does this means they consume more gasoline?

In: 6

Answer 1

Piston rings and other various seals wear over use and time and fluids that aren’t supposed to be in the combustion chamber sneak in. Blue/grey smoke is Oil. White/grey smoke is coolant. Black is fuel.