I'm interested in your location.
Refineries produce Winter Grade Fuel that is automatically sold to customers here in North Western Canada. Two weeks ago we had -40 daily over a period of 8 days. Diesels never Jelled off. Winter grade fuel runs ( process at refiners) start at the Refineries in early Fall.
I ran my Case 970 ploughing Snow that sits out side with a block heater. Same for my 2006 Dodge Ram 3500 Cummins.
I's suspect other than just Diesel in your machines fuel Tank?
Bob...North Western Alberta Canada...........