Question

a blue colored exhaust typically means that

a. the engine is burning oil
b. a rough idle condition exists
c. engine pinging is prevalent
d. negative back pressure exists

Explanation:

When an engine burns oil, the oil is combusted along with the fuel. This combustion of oil can result in a blue - colored exhaust. A rough idle (option b) is more related to issues like incorrect air - fuel mixture at idle, vacuum leaks etc. Engine pinging (option c) is due to premature ignition and is related to knocking sounds and not exhaust color. Negative back - pressure (option d) is an incorrect concept as exhaust systems have positive back - pressure to some extent for proper functioning.

Answer:

A. The engine is burning oil