I'm running 15W/40 Rotella CJ-4 diesel oil in my 4.2L. The Jeep is doing fine on it, and I'm getting less cold startup lifter clatter than I did on 10W/30 gasser oil.
That makes it nice since it is the same oil I run in my diesel pickup. And other than that convenience, I'm not finicky about oils. For the most part, anything close to factory specs work just fine. Oil is oil. I tend to lean toward a little heavier base stock in high mileage engines.
Dodge did not build my Jeep.
1988 Wrangler,4.2L I-6, Howell EFI JP-1,CRT HEI Ign,AX15 ext slave conversion, Zone 2.5" lift + 1/2" booms, BFG 31 x 10.5, Bestop.