Comment: Lived in Phoenix for 30 years. I was always told (at leas for the cars I owned) to us a slightly thicker oil during the summer months (10w40) and in the winter months use (10w30).
Do you guys even have a cold time of the year?
I can't imagine it enough to switch oil viscosity. wait until you get 30 and 40 below
I used to run 10w40 in the winter and 20w50 in the summer on my old Grand Wagoneer, but that was a tired engine. It was the easiest way to keep the oil pressure up.
I would follow the recommendations in the manual. 5w20. I'm running Mobil 1 full synthetic in my ram now. I haven't typically run synthetic, in the past, but will be giving it a try on this truck.