An interesting article on oil/carbon buildup can be found at

www.rcaircraft.net

Click on Do It Yourself Articles "Please Visit Them"----then click on 2 cycle oil test summary

Several different oils were tested running engines full throttle hours at a time. In case you don't want to read them, the conclusion was that Bel Ray HR-1 uses more gasoline by 15%. However, there is practically NO carbon build-up as with other oils.

Larry