I just recently got a Saito fa72 4 stroke for a Sig 4star 60 I'm building. My concern is the type of fuel it requires. I have a gallon of Wildcat 10% that shows 18% synthetic. Should I add castor or can I run with this? All my other engines are 2 stroke os and evolution. Never had a problem with those that wasn't other issues. I just don't want to make a mistake with this engine.