I don't think WD40 is the best thing for freeing rusty motors. It removes the oil from the cylinder walls and causes more rust when it evaporates.. Marvel Mystery oil works better and I read on here that deisel fuel is better than the mystery oil. Turning the oil pump with a drill is important if you don't want to ruin the bearings. If it has a lot of rust in the cylinders it may break some of the rings when you turn it over and you'll have to rebuild it anyway.