On Mon, 26 Apr 2004 05:32:43 GMT, (Ben Jackson) wrote:

I usually pump my own, but today I called ahead and had the FBO fill it
for me (only 53 cents more/gal!). I wasn't even present for the fueling
so I was extra paranoid during preflight, and I swear the 100LL was not
as "blue" as it usually is. It smelled like gas, and when I finally got
a big enough sample you could see a slight blue tint, but on a dip tube
I would have sworn it was clear.

IIRC, mixed octane avgas blends (resulting from mixing different
grades together) result in a clear or undyed apparance.