all marine oil is also certified to work and work well. Full synthetic marine is amazing stuff, most 2 stroke marine engines in jet ski's were also power valved and need a specific oil that wont gumm up PV's at all. Some of the engines will rev really high for long periods of time also using ANY tcw3 certified oil will result in a well protected motor' Usually a gallon of marine is not to bad in $$$ sometimes i can even find the good synthetic on closeout for next to nothing. These certified oils seperate from the fuel much better once inside the motor and usually will leave an oily film on everything.. It is obvious how well an oil works when you have to split the motor and you are poring out raw oil from the insides. instead of a dry gummy film thats just stuck on the piston in spots.
Most all atv/ dirtbike oils are NOT certified..