I have a '95 4-cyl.
I just run 10W-40 of various brands. No additives. Nothing special. It's what I love about jeeps, especially the older ones. They're simple and not terribly picky. 113,000 miles so far and tight as a drum. Doesn't burn or leak anything.
Now I have a '99 Boxster that's insanely picky. Requires a specific oil... Even requires a specific coolant. Love it, but don't drive it much.