geez oil is not as diffucult as many make it out to be, holy smokes. the most basic rule is a low number for cool climates and or a tighter tolerance engine, and a higher number for a warmer climate and an older or just looser engine, and multi grades for having the brains to realize they are for a combination of climates.who knows what the W stands for in the multi rating,I do, and a few do here also, ... like batterys i have learned all i know from calling the 800 numbers on the backs of the products, one will find almost all tecs on almost all products say the same things, some can say it alittle easier than others though, one super important rule to remember ANY OIL is better than NO OIL, and ALL OILS MIX!!!!!!!!!!!! oh yes they do, geez this is a very very dead horse for sure, read the label what you think uis the right one for u is the right one,I live in northern NJ straight 30 is fine here, 15/40 is better , OH and a detergent oil is for motors with filters and NON detergent oils are for motors without filters, as long as we are on it, a filter can pic up the gunk broken free from a detergent oil , in a motor with no filter u do not want that gunk if any to break up, unless u are going to ghange it after each use, as important as this issue may be it sure can get silly.....Randy