I've sworn by xdp's additive for awhile, but i don't think I'm going to continue to, due to the other day I had my fuel partially gel up... It was around 0* for a few days here in pa. The fuel was still sloshing in the tank, but I lost fuel psi. Put in some ps diesel 911 to save the day. Fuel psi came right back, so I think I may go back to ps. I'm highly irate about the xdp polar d gelling up at only around 0*.