to the original question about whether to use Prist or not to....
Guess, one can say, if it is required for your aircraft as per AFM / POH, then you have to use it..
but be advised that that is for pure fuel anti-ice reasons..
Any angi-fungal properties are not only highly in doubt..
PRIST themselves do not claim that anymore on their web-site ( and not because it would have been inconvenient or complex to certify it for that use..)
on the contrary, relying on PRIST, TOGETHER with bad fuel tank draining practices can create enormous problems..
called "apple jelly", that stuff is known to have sent FCUs south, engines have stopped or behaved erratically..
So draining the tanks everytime is of utmost importance..
even if the plane does not fly...planes "make water" in the tanks just by the temp diff between night & day..
Questions & Answers: Prist Hi-Flash
http://swri.org/4org/d03/fuellube/pe...es/03-4371.pdf