Good Morning Jina, to answer your question in regards to the gelling up issue you are having with the humvee, the easiest and cheapest thing to do, would be to pre treat the fuel with a quality winter fuel additive. keep in mind that if the fuel has reached a point of gelling in its current state most fuel treatments wont fix the gelling at this point. we need to be conditioning the fuel prior to gelling to prevent gelling from happening. generally any off the shelf winter treatment will do. Amsoil, optilube, and FPPF are all quality treatments. FPPF can be bought at any O"rielly auto parts stores. If the humvee is in a state of gelled up then there are a couple "rescue'" tretments out there that will melt the gell out of the fuel. or get the vehicle in some place that it can be warmed up and thawed out, and then start the pre treat in the fuel to prevent from happening again. keep in mind gelling is caused by water content in the fuel from wherever you are purchasing diesel fuel from.
Power Serv or Total power. You will need to find a way to heat back up though.
Thanks! Your answer is awaiting moderation.