Oil changes if what ever oil you chose is good for your machine the is a good choice. I run a Top Gas Dragbike that's a 8:20 index. bike will run a bit better 7:90's @ 165-170. I run Motul in my engine/trans combo. It does use the same oil for engine and trans together . A day at the track and i change oil, $25-30 for an oil change is good peace of mind. I to have more in my engine than a lot of people. Just in parts for the second back up engine was 8500. That's no machine work ether . I am changing my RD350 out for a Banshee enigne in my Outlaw Sprintkart . I will keep in mind what type of trans and gas mix suggested on here. There's good write up on what happens to oil when it's run through a trans . Lots of shear effect on the oil .