Hi,Ralph! If you're going to run it at top rpms then go to a full synthetic 2-cycle oil and run it about 40:1.If,however your engine is not straining,and you do a `plug chop'and you're not running too lean,just ENJOY that excellent top speed.Heck! Most of us don't go over 35mph very often,unless we `hop-up' the engine.So enjoy your success.