If you take that truck out if frigid winter temps, a syn is a good idea. I'd buy a good one, not a cheapo (there is a difference in synthetic oil quality). The 3 or 4 year oil drains with syn would be OK, or 2 years with conventional. You're burning or leaking some, and the oil you add replenishes the additive package in the oil. Or, just any good brand conventional 5W-30 and a good filter, your yearly oil changes, and you have peace of mind.