I would have never thought of making my own fuel but here is what I have:

Helimix is available in 10%, 15%, 20%, and 30% Nitro formula. Helimix is the premier fuel for R/C helicopters designed to produce maximum power and cooling in the harsh environment of heli flying. Helimix contains 18% oil content and is total synthetic. Helimix was desinged as a competition fuel with the aid of competition pilots. Their request was for a fuel that smoked less, made more power, superior mid-range transition, lower heat penalities, and smelled good. Lets look at each of these requests.

I use the 30% at 1045 ft. above sea level.