How much oil is left in engine after draining?
It is difficult to determine how much oil is left in an engine after it has been drained. The best way to measure this is by looking at the dipstick. However, even this can be tricky, as the amount of oil on the dipstick will depend on how much oil was in the engine to begin with. If you are unsure, it is always best to err on the side of caution and add a little extra oil.