I have had good luck with blue thunder fuel. I was told to run 15% in summer and 20% in winter by the geniuses at my local lhs. I bought 20% at the end of last winter so I used it in the summer and had no problems so I run 20% all the time. I did have a problem with some blue thunder going bad cause it was old. I had just bought a gallon and then I bought another Tmaxx that came with a gallon of blue thunder with it. By the time I got about half way through the second gallon it went bad. It changed color from blue to almost green.