I have had three diesels in my time, and lived on the northern edge of Wisconsin. Run 5-40 synthetic oil in the winter, your truck will start as easy as a gas engine, with no need for long warm ups. Also always added an additive in the winter for piece of mind on fuel. I used Howes, and never had problems. Change, or bleed off your fuel filter in the fall. Also pay attention when getting fuel in the winter, if the pump seems to be running real slow when its cold out, stop filling, and go to another station. I really miss my diesel trucks when towing.