If it's dual rated GL-4 GL-5 on the bottle you'll be fine.

The additive package for GL-5 use  to attack the yellow metal (brass, bronze) in the synchros.    They've either changed the additive package or added more additives so that doesn't happen anymore.


The only possible problem would be the GL-5 is too slick for the sychros.       If that happens,  take it out and save it for the transfer and diffs.....

Interesting, i would like to hear Aisin's stance on it as there's so much internet hearsay out there on this subject.  I found one thread where a dealer was putting 10W-30 in these transmissions, and other threads saying that the gl-5 was a typo blah blah blah....   

The challenge i have is if i even want to run gl-5 gear lube in the trans, its damn near impossible to find stuff without the limited slip additive in it at the stores.   

As for the dual cases i run full synthetic either mobil 1 or castrol syntec 75-140 and fill up the front case and let it soak through.