I've got a 68 Kaiser and have never used it in the winter. With winter knocking on our door step, should you do anything to the diesel fuel to keep it from gelling? I am told that the suppliers switch out to a winter blend. If your tank is already full of a non-winter blend, then do you use any type of additive? If your tank is partially full of a summer blend, then you fill it up with a winter blend, do you use an additive and if so is there anything special that needs to be taken into consideration so you do not create some witches brew or make things too rich? If using an additive then which one is best?