These bikes have wet clutches and do not like friction modifiers in the oil. There is an excellent thread in the Technology Forum called "Oilology." Shell Rotella T 15w40 dino or Shell Rotella T6 5w40 synth seem to work very well in our Shadows.Thanks for the good advice McPenner; noteworthy point about oil. I have a '63 Lincoln and the conversation among collectors is all about the disappearance of ZDDP from modern oil due to EPA regulations limiting phosphorus content. So I am using ZDDP additives in my old 430 MEL engine. Not familiar with these Honda engines... besides fresh oil are people advocating adding friction modifiers like ZDDP? I think eventually I will read this entire board, but these newbie posts are a nice shortcut. I appreciate any advice.