Question 225Motor Plants - Assistant Engineer

The correct answer is D) quality of the oil. The proper lubrication of a diesel engine requires two important considerations: the delivery of the oil in sufficient amount, and the quality of the oil. The quality of the oil is crucial as it affects the engine's performance, efficiency, and lifespan. Factors such as the oil's viscosity, additives, and purity directly impact the engine's lubrication and protection against wear and tear. The other options, such as cetane number, pour point, and viscosity temperature, are important engine parameters, but they are not directly related to the quality of the lubricating oil.