GarthH said:It is certainly possible for diesel fuel to gel while operating. It varies depending on the grade of diesel fuels.
You are right, it is possible.
But the most probable time for a diesel to gel up is in the first few minutes right after starting. That is when the fuel and fuel system are at their coldest. Once you can get some warm return fuel recirculating, and engine heat warming the fuel filter, you are usually good to go.
That first five minutes usually lets you know how your day is going to go.