Folks,
I was meerly pointing out that filling equipment is not necessarly "laboritory exact". I was not trying to stir things up. I disagreed with Eagles comment on placing a mark on the bottles for his above mentioned reasons.
Simple fact of the matter is that variences do exist, weather it be in the botteling equipment or the flex of the bottle if using optical measuring.
I would even venture to guess that at least one manufacturer puts an ounce or two more in the bottle just to make it look fuller than the competitions and to account for any fractional variences' in botteling machines or inconsistencies in bottles from batch to batch.

Bottom line is fellow fliers: whatever the variences involved, expansion coefficients, botteling, tempreture, etc... none of it will have a great enough effect on the finished product (assuming the manufacturer has consistent practices or quality controls in place) to tell the difference in the way an engine runs.

I've mixed my own fuel on and off for years and I can not tell the difference (and neither could the engines) between 19.75% oil and 20% oil or 20% nitro and 20.25% nitro. How does this relate? - Any fuel maker out there that puts their name on a bottle (or can) is certainly going to make sure that the tolerances in their product line are going to be within a certain fixed percentage, and I would assume that the variences' would be so fractionally small that anything but an extremely expensive laboritory test could determine the varience. I'm talking small fractions here such as .001%.

Now back to the original question of coeficients of expansion.
I searched a bit then got on the phone to a relative who is a chemical engineer. Although he did'nt have any data at his fingertips, he did mention that the compounds in question would have such a small expansion rate in the liquid form that it would be nearly impossible to measure in the tempreture ranges that blending would occur at (told him the temp ranges of 40-100 degrees farenheight). He did mention in his line of work, they are only interested in molecular weights (rathar than volume) since they are constant.

Sorry to ramble on guys. I guess I got a little caught up in the "off subject" part of the thread.