I always find it a pain as the sump nut is on the back of the sump + I always get a shed load of oil all over the place. This thing is quick and very clean, plus its easier to dispose as it collects it. As for the leaving sludge at the bottom of the sump - ive been told that it doesn't do that. I know that Merc & BMW dealers use this method, infact i think that new mercs dont have a sump plug at all. Plus i change oil / filter every 6k. I just wanted advice as on some cars the pipe cannot get to the bottom of the sump, so if anyone has used one i'd be glad to know how succesfull you were