I did some cold weather tests of my homebrew BD based on overnight unheated drive shed sample observations last year and came up with the following temp guide:
B100 down to 45-50*F I want to take no chances especially with BD made from solid at room temp grease
B50 from to 45 - 35* F
B33 below 35*F and that got me down into single digits below zero
I mix in it the fuel tank with ULSD and a measured shot of PS Grey or White depending on what I have on hand.
Absolutely no gel issues

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1981 240D 143k 4 spd manual -SOLD

2004 VW Jetta TDI 5 speed 300k -still driven daily