For the VW TDI (15 gallon tank) I put in a gallon of kero with a few oz. of Howes, then fill with D2. With the Cummins, I go 2-3 gallons of kero, adjust the Howes amount accordingly, and fill with D2. Works well.

 

ive been working in the north western part of north dakota and we have seen temps in -40 range with no wind .i used howes,a little more than they say to but still no problems but also was using #1