I liive in NC, near the coast, what oil would you suggest.

May just be a valve tapping, try tightening the rocker arms, this is common with Jeep 4.0L engine.

I also have a 1995 wrangler 2.5 motor @ about 125,000 it developed a rattle in the lifters. i've talked to some mechanics . They said the litters are not adjustable all you can do is change to a heavier weight oil like a 20w50. But I just run the standard 10w30 recommended by owners manual. The mechanic said it wouldn't hurt anything to rattle thicker oil just quiets the noise and will kill your gas milage. I am the original owner bought in oct of 1995 with 14 miles on it . My jeep (blackheart) now has 215,000 miles and is getting it's first new radiator.