What is the recommended engine temperature when changing oil?

The recommended engine temperature when changing oil is a warm engine because this ensures that the engine oil is at a more optimal viscosity for draining. When the oil is warm, it becomes less viscous, allowing it to flow more easily out of the oil pan and remove contaminants and deposits more effectively. This is particularly important for ensuring that as much old oil and debris as possible is expelled during the oil change.

Additionally, a warm engine helps to facilitate the cleaning of the oil system since contaminants suspended in the oil can separate and settle at lower temperatures. Changing oil when the engine is warm reduces the likelihood of sludge build-up and allows for a more effective oil change.

In contrast, using a cold engine could result in thicker oil that does not drain as efficiently, potentially leaving some old oil behind, which could compromise engine performance and longevity. A hot engine, while it may seem beneficial due to oil fluidity, can pose safety risks, with burns or difficulties accessing components due to high temperature. Changing oil at any temperature isn't ideal as it disregards the need for effective drainage and cleaning of the system.