What freezing point of ultra low sulfur diesel?

Diesel is a mix of hydrocarbons, and the components have different freezing points. For Number 2 diesel, as the ambient temperatures drop toward 32 degrees F (0 degrees C), it begins to cloud, due to the paraffin in the fuel solidifying. As the temperatures drop below 32 F, the molecules combine into solids, large enough to be stopped by the filter. This is known as the gel point, and generally occurs about 15 degrees F (-9.5 degrees C) below the cloud point.

This wax then forms a coating on the filter which results in a loss of engine power. The same thing happens on starting an engine when the temperature is below freezing. The filter becomes almost instantly coated with wax - usually, enough fuel gets through to allow the engine to idle, but not attain operating RPM. There are two common ways to overcome this: one is a diesel additive, the other is a fuel heater.

In Alaska and other colder climates, trucks are running regularly at minus 51 degrees or lower so as you see it depends on additives and heating but to freeze as in turning solid you would need laboratory conditions as nature cannot go cold enough to freeze to a low enough temperature.