i have alwayse wondered where they get the designation for motor oil weight!! i know its kinda off the wall, but quite honestly ive alwayse wondered, but never really asked!! so, i know for example 5w30 is the oil weight, but in all honesty, what in the hell does that mean?? and im sure there are otheres out there that could also benafit from this info aswell,,,, so school me!!!