No you can change man you will have to retweak the tuning. I know guys that have ran 6 or 7 gallons through an engine and they ran 3 diffrent types of fuel a coupel gallons odonnell a gallon trx so on.. Its cool also rob was talking about the oil. Trinity is made by wildcat who uses the best oil out there. That is why they have a lower oil content than some others. 12% oil in that will be as good as a 16% TRX which is made by powermaster a lot cheaper fuel...X