I have lived up at 8,000+ feet in the San Juan Range of the Rocky Mountains for the last 10 years and we get down to minus 25̊F and colder every year. Prior to moving here I have operated equipment in the Artic, the Sierras, and even in Siberia in the winter so Arctic Cold is no stranger.
I usually leave my F250 in my heated garage. I’m a Captain in the local Volunteer Fire Department and after midnight after a night fire I leave it outside next to my garage side door. Usually by the time I return home my garage double doors are frozen shut and I don’t feel like the hassle. The problem in the morning then is to dig through 2 to 3 feet of fresh snow to find my door handle and sometimes have to hit the top and rear edges of my doors with my palm to break the ice. I should preheat my Engine but rarely do but if I follow my own recommendations shown below it always starts right up and I have immediate oil pressure.
Since new I had used Delo 400 Multigrade SAE 15W-40 Oil and a Purolator Premium Plus P/N: L44872 Oil Filter. A few years ago I found the Napa Gold Full Flow Oil Filter (Wix 51734) to be a better oil filter and still use it every oil change.
About three years ago when Mobil introduced the Fully Synthetic Mobil 1 Turbo Diesel Truck 5W-40 Engine Oil, (API: CJ-4, API: CI-4 Plus) I switched over to it for my backhoe tractor and I was so impressed by its performance that two months ago I started to use Fully Synthetic Mobil 1 Turbo Diesel Truck 5W-40 Engine Oil, (API: CJ-4, API: CI-4 Plus) it in my F250.
https://mobiloil.com/en/motor-oils/mobil-1/mobil-1-turbo-diesel-truck
Starting with my 1989 7.3L F250 after my Stanadyne Fuel Injector Pump failed I’ve used Stanadyne Performance Formula Diesel Fuel Additive at every fuel refill. I still use it in my 2000 7.3L Engine which does not have a Fuel Injector Pump but now I use it to prevent Diesel Fuel Jelling, increased Cetane, Injector cleaning, etc. Its well worth looking into especially for cold weather. I use it all year and as the Fire Department Trucks Maintenance Officer I use it in all our diesel Fire Trucks.
Performance Formula « Stanadyne Additives
To prevent Diesel Engine Cavitation in my 7.3L I use Low Silicate Fleetguard P/N CC2825 ES Compleat Extended Life Ethylene Glycol Antifreeze/Coolant 50/50 Premix. Read the following regarding Cavitation:
7.3L IDI Cavitation
Our Ford 7.3L Engines come with Cavitation Protection since the early 90s but if you changed out your Coolant using a regular Antifreeze it can cost you!
https://www.cumminsfiltration.com/html/en/products/cooling/coolant/es_compleat/es_compleat.html
To maintain good cold weather starting I use Lead-Acid Napa Legend Batteries manufactured by Johnson Controls, 12 v, Napa P/N 7565, BCI Number 65, 1,000 Cranking Amps @ 32̊F, 850 Cold Cranking Amps @ 0̊F.
Good luck, the above has worked for me.