year - around oils for D-4

I need some advice on what oils to use in my D-4 for year around use. I am in Nebraska so it can get to -10 to -15 below in the winter when I will be using it for moving snow. Alot of new oils out there like 5w-40 etc for the engine. It does have an 1500 watt external block heater, which is going to help. Any suggestions for the transmission, hyds, final drives. I wish I had a heated shed as that would be ideal, and she wouldn't fit in the garage,well maybe,😞

You could look at synthetic oils like Amsoil or Redline. They both have products that would work. For the hydraulic oil you would need to look at automatic transmission oil but for the transmission and finals they have hypoid equivalent oils.

Kevin