I live in evergreen, Co so its freezing every night. I've heard rotella is great in these 4.0 s but what is the general consensus on what's best? 99 with 130k.

Slippery oil works best in these engines.

I use Mobil 1 10W30 w/ a Wix Filter.

Rotella T5 syn blend 10-30 with a wix filter.

A 4.0L would last half a million miles on 80W-90 gear oil lol, imho the brand of oil isn't that big of an issue as long as its there and changed regularly. With 335,000mi on mine and a previous owner that neglected it BADLY I'm running Super Tech or Castrol 20W-50 whichever is cheaper and a Mopar MO-090 filter. I haven't tried the Rotella 15-40 that many here seem to like due to the Zinc content, but tried a different 15-40 when I first got the Jeep and it didn't like it lol.