My "old mechanic" father used to drain the oil out of an engine, fill it with Varsol (a solvent that's no longer available), start and run it for 1-2 minutes, drain the Varsol, remove and replace the old filter and fill the engine with fresh oil. I don't do that any more, either.MPlunkett said:When I change my fuel filter, I prefill the cannister with a quart of ATF. Its easier than keeping diesel around. A retired Cummins mechanic showed me the trick, I was a little hesitant at first, but it is supposed to clen out the engine ..... My two cents