i still havent done an oil change on mine but it is impossible to not drain it properly UNLESS you stick the drain plug back into the oil pan with oil still shooting out full force, i have to do like 3 crappy oil changes a day at lexus amung other things but its virtually impossible to screw up draining the oil. now filling thats another issue, i couldnt tell you if they put enough in or not, but i assure you all your old oil was drained.