I USE HOWES LUBRICATOR FUEL ADDITIVE . AVAILBLE AT MOST ALL MAJOR TRUCK STOPS, I HAVE A 2001 F-250 SUPER DUTY 4X4 7.3 POWER STROKE AND IT HAS CRANKED AND NOT GELLED UP DOWN TO 12 DEGREES OUTSIDE WITH OUT BLOCK HEATER BEING PLUGGED IN. HOPE THIS HELPS Login to read more.