Final answer:
The correct answer is option D) warm.The best condition for changing engine oil is when the engine is warm as it allows the oil to flow out more easily compared to when it is cold, but care should be taken to ensure the engine is not too hot to prevent burns.
Step-by-step explanation:
When changing the engine oil, it's best to perform the service when the engine is warm, but not hot to the touch. This is because warm oil will flow more easily and will help ensure that more of the old oil is drained out, as opposed to when the oil is cold and more viscous. However, the engine shouldn't be scalding hot, as this could pose a risk of burning oneself. Typically, running the engine for a few minutes before starting the oil change process should be sufficient to warm up the oil. In contrast, trying to drain oil when it's iced or when the engine is cold can result in a less thorough draining.
When changing the engine oil, it is recommended to warm up the engine to operating temperature before draining the oil. This allows the oil to flow more easily and carry away any contaminants that may have settled in the engine.
Operating temperature refers to the optimal temperature range at which the engine performs efficiently. It is typically indicated by the engine's temperature gauge reaching the midway point between the cold and hot marks.