Removing sludge won't make them go mushy....
I don't know if there is really a problem, I've not seen any with the
B5 or B10 I'm getting at the COOP here (not labled, might in fact not
be biodiesel, for that matter!).
However, biodiesel is a fatty acid methyl ester, not a linear
hydrocarbon like most of diesel fuel is (the rest is sulfur compounds
and cyclic molecules of various sorts), so there could easily be
incompatibilities -- the biodiesel is much more polar and may soften
and/or penetrate rubbers compounded for exposure to non-polar
hydrocarbons.
Peter
