i had followed the service manual for my 98 wrangler and had added some 75w 90 GL5 "master craft" to my tranny. I drove it around for about a week and noticed that it wasn't shifting as smooth, had trouble finding 2nd gear, and i could almost feel the metal to metal contact in the shifter.
After posting my conscern on WF CCain had rec. that i use a GL4, seeing how GL4 is whats rec. I guess there is a typo in the service manual all service manuals!
Sweet, so i spent another $50 and picked up 4 qrts of MT-90 75w 90 GL 4
What a difference! Very smooth, effortless shifting, no metal contact feel, and each gear is very easy to get into, down shifting too. I strongly rec.
RedLine MT-90 75w 90 GL4 to be used in you AX-15 tranny
p.s. - save yourself about 1 hr and pick up a cheapo $5 hand pump to get your gear oil into the tranny. After about 2 minutes of squeezing and manuvering with my bottle and some old battery breather tube, i had enough. That little bottle pump made it effortless and quick