I put this in the motorcycle section since it pretty much deals with high reving motorcyles. My question is i ususally have been using 10w40 valvoline oil(not motorcycle) in my ski for the past 103 hours i have had it(its a honda aquatrax f12x turbo 4 stroke ski). Ive changed the oil about 3 times now, and the recommnended interval is 50 hrs(i decided to change it more frequently since i had auto oil instead of the overpriced motorcycle oil. Next season, im looking for some good 10w40 synthetic oils that would help me be more confident in letting my ski g2 50 hours without changing the oil. Usually the top speed is at 60mph(gps, not gauge speed) and its rpm averages about 6200 rpms at wot. What 10w40 oils would hold up against this, and do i really even need synthetic motorcycle oil since i don't even have a wet clutch?