If it was my TJ I would run the M1 [email protected]
5W-30. I've been seeing the 5qt jugs for $20 at Wallmart. My Bro's 98 4.0L UOA's showed lower numbers with 40W oils but I really don't think that shows the whole picture. B/C I know of many 4.0L's well over 200K on bulk 10W-30.