I was running 20W50 Full synthetic in my YJ, had a seal fail in BF Wyoming,
the dealer changed the seal but all they had was the "real" AX lube so I went
with it. It shifted way nicer, but it is wearing out after about 12000 miles.
I pulled the plug and checked it, no particles, but its getting dark.
The synthetic was good easily for 25K. This is the 4th tranny in my YJ
either new or rebuilt in 200K and its been in there since 125K. So I'm happy with the oil.
Going back to the Redline synthetic.
I should note that when my trans was rebuilt teh last time we used all
un-shrouded bearing instead of the stock shrouded ones.
Toyotas with the same tranny came from the factory with the synthetic 70w85 Pensoil in them in 1985,
also coincidentally the only year in the 80's to NOT have bearing problems. The earlier trucks had a weak
input bearing and 5th, later ones had a new tranny that had other issues.
YMMV
Dave