Previous owner "upgraded" the tires to 265/70R15s which work great in the snow, but they're crazy huge and heavy. Regardless of tires and pressure I only get around 15-16mpg below 0 degrees F for my short daily drive.
Changed engine oil to Mobile1 0W30 eco. Smaller tires, 215/75/R15s. Tire pressure is about 35% above suggested max. (60 with a max 44). 200 watt oil pan warmer. Got up to 23 in the warmer weather until I bought the motorcycles. That dropped the mileage on this vehicle considerably because I only drive it in bad weather now, but driving a 50+mpg motorcycle instead of this 23mpg truck when I can only makes sense.
Fluid swap with full synthetic, trans, diff and transfer case. Add a bed cap of some sort. Now that this is 15 years old, I'm looking for a BEV for a daily driver and this will just be a work/snow truck.