Run a Synthetic Blend 10-40 for the winter.
Rotella T5 15w-40 is good too
Mobil 1 Turbo Diesel Truck 10w-40 has a pretty good amount of Zinc and it's a little cheaper than the 15w50 (wally mart) and is full Synthetic.
More important is regular 5K mile oil change or sooner with good proper...