I've been running 15 % Omega for years..2 strokes 4 strokes OS Saito....never have had a problem....IMHO....whatever you're running 10 15%whatever, pretty much stay with the brand and nitro content consistantly...if you switch every gallon then your going to be re-tuning the engine alot....now it doesn't mean you can't switch content and brands...you will probably have to re-tune that's all...