ORIGINAL: YearningtoFly
kid at hobby store sold me 15% synthetic cool power............no castor
found manual for motor it says do not run in with synthetic you need castor
argh where are my golf clubs
Not really an issue unless it has less then 18% oil overall. Castor just gives you a little more protection if you run too lean. Set the needle correctly and it's a non issue. I run nothing but synthetics in my engines.