Where did you get fuel in December that wasn't D-1 winter? If you're further south, might always be a good idea to ask the attendant if they've switched over to D-1. A bottle of White PS with D-2 should help some, if you can't get D-1. The accessory pre-heat may help for a few minutes, but you need to get some good winter stuff in the rest of the tank, or you risk gelling up again.
-5ºF...that's starting to get cold.
I was driving around in -5 to -10ºF in late-October. Guys out in the prairies are getting their brass ones handed to them in the -10 to -15's...brrr...
Stay warm!
Cheers
D.