Dyes doesn't do anything for your rc engine's performance.  Its all a marketing trick. 
If you dont have any clue abour RC fuel, which one would you pick if you are in the hobby shop.
Wouldn't a blue fuel (or other cool colors) attract your attention?
Only purpose I could think of, is to identify the liquid.  So it could be distinguished from other liquids that we may have stored at home.

Od's are almost clear, a little yellowish, but I dont think they did that on purpose.  Best one I've tried.

I had left over blue fuel before, left it for a long time, and the dyes actual settled to the bottom of the bottle.  (That couldn't be good)


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