I know this has probably been beat to death over the years,but Ill ask anyway as I havent been here!"Back in the Day" when our bikes were made, oils left much to be desired and had little variety.Nowadays with modern metallurgy for our engines,and superior chemistry, should we stick to the manual recomendations that calls for SAE 30? or is 20w50,15w40 acceptable? or as good? anyone have any knowledge of whats best now? i know my last Norton Commando preferred 20w50 over 30 (no wet sumping, BIG plus!)and I beat that thing like a dog!