Is it cleaner to change engine oil by draining or suction?

[McLily]

Changing engine oil by draining is the cleaner method. The reasons are: The drain plug is located at the lowest point of the oil pan, which allows almost all the engine oil to be drained out. At the same time, you can visually observe the condition and color of the old oil during the draining process, which helps in assessing the engine's working condition. The sediment and impurities at the bottom of the oil pan can also be drained out, and the metal shavings attached to the drain plug can be cleaned in time, avoiding contamination of the new oil. Information about oil change is as follows: 1. Lift the vehicle, remove the underbody guard, and loosen the drain bolt on the oil pan. This is a common method for oil change, but the disadvantage is that the draining time is longer, and there may be some residual old oil left in the oil pan. 2. The suction method uses vacuum gas to create suction. The suction tube of the suction device is inserted into the oil pan through the oil dipstick to extract the oil. This method is faster, and most engines will have very little old oil remaining.