The schools don't shut down for the day in the interior unless the daytime high temp is going to be below -50F. The worse I was it was in '82 when the temp dipped to -72F. Most of the winter, most daytime highs hover around -20F to -35F, with overnight lows typically around -40F. And there is the wonderful Ice Fog.... when the moisture in the air freezes and cannot drop due to air density. And Fairbanks, by sitting in a river basin, is the Ice Fog Capitol. Last winter there, the kids wanted to go trick or treating on Halloween. Took them around in my Bronco. They went to door, got goodies, and jumped back in the Bronco for the next house... temp was -32F that night.
It would be stupid to run a diesel from Oct thru April, as there is no need to. I mentioned what the locals do in the interior. My advice is to have a good block heater, oil pan warmer, and battery blanket. Fuel is setup for that weather and is usually #1 diesel with additive already mixed in. But you better keep fuel filters at the ready, as nothing is fool proof, and Murphy's Law will kick in when you least expect it. I would also advise an Arctic Fox inline fuel warmer. Play games with oil all you want, but if one doesn't use common sense methods that have stood the test of time, don't blame anyone because the pickup won't start and has to go in a shop to thaw out. I lived outside of Fairbanks, and the first snow in my area was usually around Labor day on Donnelly Dome, with the first snow on my door step within two weeks after that, and the ice didn't go down the Chena river till end of breakup in May. That is a long stretch of time to run a diesel continuously.
Also, go over the Alaska Tent and Tarp in Fairbanks and have them do a winter front for your pickup. They have the best! Don't settle for some online winter front that they sell down here. Another one of those wise investments you can make. And when it gets really cold, you can see what the infamous "Fairbanks Square Tire" is all about after the vehicle sits overnight. You will think you are riding in Fred Flintstone's car!