Well, from what I've seen, if the engine is broken in correctly, and taken care of, i.e. after run oil, not over heated, about 6-8 gallons isn't rare. So after about 8 gallons, for an OS .12 cv, you spend 27 dollars on the piston and sleeve from duratrax, tapered chrome plated, and you're back in business with a brand new engine... almost