10W30 or 40. It will just be noisy until it dies and that could be years. Typical of an older motor in a Jeep. Just continue to change regularly and you should be fine.
Some will actually switch over to Rotella which is primarily for deisel but can be used in gas engines.
Get better stereo speakers you won't hear it.
89 2.5 TBI, 4" RC lift, 1" Booms, SYE, Adams Driveshafts front and rear, Ford 8.8 with 4:88s, BFG 33X12.50X15, and a ton of other stuff.
AF Jeep Club Tail Number 184