[Vwdiesel] dyeing fuel

[Scott Kair]

    Most of us are familiar with the fact that Diesel fuel comes in two
colors- refinery yellow and untaxed red.  The latter creates a problem
because homebrew comes out red, which makes it easier to mistake for untaxed
farm fuel.
    What dye is added to make the farm fuel turn red and how hard would it
be for the distributor to dye it a different color so as to differentiate it
from experimental biodiesel?  Also, is red a universal color for farm fuel
within the States?
    TIA,
    Scott Kair