People seem impressed with a top pump for changing their oil not realizing that doing it like this you fail to drain the metallic particles in the bottom of the oil pan. This pump system became popular in the late 1930's to sell more oil at the pump block while you bought gas. Do it yourself and let the warm oil drain for an hour from the pan. If you are fanatic about cleansing your engine you can next mix a 1/2 oil and 1/2 kerosene mixture.......run the motor at idle and lightly rev it several times for about 15 mins....... re drain as above, and ad new filter and proper oil. Like I said, if you are fanatic. Good luck, Tomygun