I haven't tried anywhere near all the oils available but so far I've tried Honda, Royal Purple, Mobile 1, Ams Oil, and finally Rotella T4 and T6. My 750 never seemed to mind what oil I used but I could tell differences with my 83 GL 1100 interstate and that difference was on how smoothly its transmission shifted and so far my Goldwing likes Rotella the best. It was fine with T4 but one time during an oil change, no store in town had T4 in stock so I had to settle with T6 ...... and the Goldwing seemed to like it even better. No scientific data to prove/disprove and one could argue it's my imagination but I use Rotella in all my bikes. Is there a better oil? Probably but Rotella T4 or T6 is good, affordable and easily available for me.