M. Trans lube for economy

Anyone know the model # for the ECO trans (2012) M32 ?

Does it call for GL-4

Amsoil MTG 75/90 is this a shifting improvement?
How about viscosity & drag compared to stock lube.

Any warranty issues?

Other "Econo" substitutes?

Thanks

AMSOIL Manual Transmission & Transaxle Gear Lube 75W-90