Every oil is made different! Whether it's Castrol, Royal Purple, Valvoline or any other brand. Each oil has different chemicals in it for the oil to perform the way the manufacturer wants it to work. Even from different brands like Valvoline and Castrol the oil maybe the same weight like 10w-30. But, it'll have different chemicals in it. In the case of scooter oil it's designed for the high heat and high rpm. So as long as you use a good aircooled engine oil that will handle the engine revs of 8,000 plus? Which I recommend Valvoline, Royal Purple or AMSoil. AMSoil and Royal Purple are both fully synthetic and both have specific oils for single cyl. air cooled motors. Another benfit to synthetic is you can run them in your scooter for longer periods of time. So you increase oil change intervals.