Cp140: I've asked two fuel manufacturers for that information. One replied that he didn't have the information, and one answered another question, but ignored the question about coefficients of expansion. If I knew who manufactured the methanol, nitro, etc. I would contact them, but I don't.

I don't know how much variation there is in the fuel we buy. As a manufacturing engineer with 37 years of experience, I do know that there is variability in every process involved in manufacturing fuel or any other product. That's why process and quality control are so important. I suspect that the variations caused by temperature differences in the blending process of glow fuel are insignificant, but it is an interesting question, and one that I thought I could answer to satisfy my curiosity. I'm still curious, and an still looking for those coefficients!

Regarding temperature, I'm pretty sure that the temperature of the air that the model flies in has far more impact on the performance of the engine than the temperature at which the fuel was blended, and I agree with the last few posters that a variation of a tenth of a percent or so in the percentages of nitro and/or oil in the fuel would have no significant impact on engine performance or longevity. My guess is that the quality and uniformity of the fuels from all of the the major manufacturers are good.

If I do have a ax to grind, it is with the one manufacturer who advertises and labels his product as 15% nitro and 18% oil, when the actual content is about 11.3% nitro and 15.6% oil by volume. Those differences I do think are significant. But then, that's just my opinion; I could be wrong.

At the risk of appearing maudlin, I'm going to also say this: I can remember a time when I would think twice about making a long distance call across the state to discuss an issue like this because of the expense. Now I can have discourse with people around the world (thanks for your input downunder!) for practically nothing. This is a freedom that is worth protecting. Let's all thank Al Gore for inventing the internet and RC Universe for providing this forum. Thanks to everyone who has responded, and keep those opinions coming!

Oh ya, I'M STILL LOOKONG FOR THOSE COEFFICIENTS!