heneghan@ihuxa.UUCP (Joe Heneghan) (09/25/84)
Oils can be made many different ways but most are made with two additives, a viscosity index improver and a pourer depresant usually among others. These two tipify additives used for multi-grade. The idea here is that you want the oil to flow under a range of temperatures. Oil behaves like ball bearings- minimize friction. Lawn mowers, boat engines and other special engines can use single grade. Some diesels shouldn't use the multi. But I'd be careful about making a claim against an auto manufacturer when useing single grade oil. You can use a heavy weight in the summer and a light weight in the winter if you want. Let's talk about WWII for a point of reference, correct me if I'm wrong, but a famous battle was won partly due to the fact that the Germans used heavy oil in the middle of winter and... RAAAA-RAAAAA-RAAAAA-RAAAAA, their engines wouldn't start. I would summarize by saying oil is application specific. We can say without reservation that multi-grade oil is user freindly and auto makers seem to like it in their engines.