For best results, spin right before starting while turning the engine over. Turning the engine over ensures oil passages line up to oil all areas. That being said, there are plenty of engines started w/o any priming whatsoever, such as newer vehicles using crankshaft driven oil pumps. One trick which works if priming cannot be done is to pack the oil pump w/Vaseline, this makes sure the pump sucks oil as soon as the engine turns, the Vaseline melts at a low temp & mixes w/the oil easily. My $.02,,Brian