Originally Posted by daveg13
A GL4 gear lube. One of the few available is Redline MT-90 or MTL.
Ax-5/ax-15 Use the above GL-4.
Pennzoil Synchromesh, or Royal Purple Synchromax is for the newer Jeeps with NV transmissions. Stay away from GL-5 or equivalent gear oils, they aren't freindly with internal brass parts.
One thing to note, Chrysler has superceded their AX-5/AX-15 fluid with Chrysler 10W30 motor oil. Which is pretty much the same viscosity as the GL-3 oil that was originally recommended by Jeep.
and. The Trans Lube chart on the Royal Purple website recommend 10W40 for all 98 and newer manual Jeep transmissions (except for the NV series)