[rlkf]

Mostly it's the start battery that have problems in the cold. The diesel sold in Norway have anti-gelling substances added; cars run fine in -20 degC/-4 degF.

[pard68]

I live in the southern USA. So it makes sense that I have never heard of this. We had a -6°F night the other night but usually it'll freeze at night and be back above freezing by noon.

[maxerickson]

It's likely that the stations around you switch to a winter mix.

[bluGill]

diesel starts gelling at warmer than water freezes.