How many miles should a diesel engine last?

When used under operating conditions that are identical to that of a gasoline engine, a diesel engine should last at least twice as long as its counterpart. Diesel engines operate at lower speeds than gasoline engines, which means their internal parts don't rub together and wear out as often.

Diesel engines are built to be more robust than gasoline engines because they must withstand the high torque output and compression ratio in the combustion chamber that's higher than in gasoline engines. A former Ford employee named Gary Mueller stated that he had a diesel engine that was still running after over one million miles.