I’ve been in AK for 10 years and have other than 4 years lived in long winter regions. I’m in Anchorage but we drag our camper all over the road system most of the summer. Our last 4 or so winters have been lower snow and overall milder than average. That said we’ve been getting the flip flop of fridges cold and dry to seasonally mild with precipitation then back to cold so everything freezes solid.
I’m not trying to scare you but you will be traveling some of the most remote isolated roads in their most extreme conditions in N America. In the summer there is lots of tour bus traffic but winter for the most part it will be you and tractor trailers and they can be fairly spaced out (hours). That being said you will also be traveling some of the most beautiful, untouched, natural, and raw areas, a true trip of a lifetime.
As for tires. Do you currently have passenger tires? Or ATs? Tires are the #1 factor for safe winter driving. Put a set of Michelin Pilot super sports on a Subaru (I think the winter benchmark) vs a Rwd mustang/camero/charger and the RWD wins. And as the temps drop the winter tires provide more and more of an advantage and the drive you are talking about you could be entirely on snow/ice from the time you cross into Canada until you cross back into the lower 48. We do not salt the roads in AK and on a typical winter my tires don’t touch asphalt for 4-5 months. As for chains get the cross chain style (pictured below) and remember most are sold in pairs and you need 4. And honistly if I was heading across Canada or above Fairbanks that time of year I would have winter tires and carry chains and traction mats. Also the standard recommendation is 3 spare tires...
The weather could be almost anything but pretty much for sure it will windy and dark.
The other equipment I would carry: 1 or 2 surplus style wool blankets, 1-2 cans of spray de icer, a winter windshield cover, good ice scraper and 3-4’ push broom (for snow removal), 1-2 telescoping style snow shovels (picture below), head lamps with extra batteries, took kit with battery impact driver with lug nut socket (22mm), fire starter and 1-2 duraflame logs, a propane tent heater (picture), a jet boil stove (but don’t buy one just for this). I spend a ton of time outdoors and come from a military background (my wife is still active duty) so tend to be over prepared. That said I would also have an ax and camp saw. I would also highly recommend a garmin InReach GPS and satalite messenger.
As for other supply’s/gear, the 3 items you do not want to cut corners and go top quality: Top quality winter boots rated to at least -40, I’ve worn sorel caribou’s for 30 years but there are many good options. Top quality Mountaineering level down mittens And liner gloves. Top quality mountaineering down jacket with hood at least 800 fill.
Now for the rest: good quality 60g or so insulated pants, middle weight fleece top and bottom, light weigh base layers, face mask and or baklava, ski goggles (your can tears freeze at -20 or so), a pack of the disposable hand warmers and toe warmers (they sell big boxes at Costco). Remember you want to be able to cover all your skin many people forget about face and eyes.
If the main reason is to go north of Fairbanks have you looked into ferry from WA to Seward? It would give you the opportunity for marine wildlife as well. But then days on a ferry may add complexity. Honestly the worst part of the drive will most likely be Canada.
It will be an amazing trip if I think of anything else I’ll post it up. And definitely reach out with any questions
As for fluids I don’t change them out from the standard but I’m not regularly cold starting at below -20 and Prestone brand de-icer is by far the best for freeze resistance. And I agree with keeping it running when applicable but also watch your gas you will probably get <10 mpg traveling those roads.