I spent most of the afternoon reading the fuel forums today, mixing your own fuel, and I get the idea loud and clear that not only does the percent of nitro NOT matter, (and certainly not the COLOR, for gosh sake)., that in fact most .40 and up two-stroke engines will run fine on ZERO percent nitro, just 80 percent methanol and 20 percent castor or synthetic oil. So the blowhard at your field who is griping about pink vs. green doesn't know what he's talking about. Higher nitro amounts might be advantageous with high-performance is required, or at lower ambient temp climates. Some say castor is better for engines, ringed or not, some say synthetics are just as good or better, some use a blend. There's no consensus that I have seen. Most think castor or a blend is the way to go. I've never had any problems with my glow engines with 10 percent nitro fuel... And the freakin' color is any color you or the manufacturer decides to tint it with!