Probably one the most important things is blended fuel for the colder months ( generally transitioned by early Nov. around here), but not always. We were hunting right at Thanksgiving, bought fuel at a truck stop...one day later, the temps fell to -20 F and we promptly jelled-up. Made for a pretty miserable experience ( my first Diesel and about 3 months ownership), when your boondocking miles from anyone! Bring along some Diesel winter additives and you'll be fine. I've started my old '97 Cummins at around -23 F, without being plugged in. She started off a little rough, but was "purring" pretty quickly. Oh.... and we run synthetic oil in the crankcase!