75W-90 gear oil for both diffs and transfer case

That’s seems counterproductive to their profit margin on Toyota branded fluid sales.

 

Maybe not that big of a deal for them since they are now charging between 53K and 83K for new vehicles.

On the OP question note; dependent on the year it may be different, but my 2012 owner manual has
-2012 Owner Manual: Front and Rear Differential: 75W-85 (but as previously stated, my toyota dealer uses only

$39 75W-90 GL-5 Limited Slip, Ultra Long Drain 500k Miles, Manual Transmission, Gear/Differential Lubricant (1 Gallon)

75W-90 which IMO is fine as its not that big of a difference from what the manual lists)).
-2012 Owner Manual: Transfer case fluid: 75W-90 (So this works out for using the same fluid in Diffs and in Transfer Case (Which is what mechanics have been doing for years anyway)).

 

75-90 in diffs and t-case with no issues so far.

 

I put 75-90 in all three and I’ve never had a single issue. People seem to forget that as time goes on, the EPA and other stupid gov organizations keep pushing the mileage thing. Manufacturers are using less viscous oil to try and squeeeeeeze a little more fuel economy. Take the 20 tundra oil weight of 0-20 vs 5w30. Both will work. 20 is lighter for fuel efficiency.

i got rid of that oil a week after i got my tundra w 7k miles and have been running full synth 5w30 and i see less dark oil every change. Same can be said for my diffs and my t-case.