Where to Get Gear Oil

Just to correct your misconception, Toyota does not call out either GL-5 or GL-4 in the owner's manual. Look under Specifications section 8-1, it asks for LF. The additive in GL-5 would be wrong for the transfer case. My understanding (haven't yet opened my xcase) is there is a brass part in the case that should not be exposed to the GL-5 additive.

There are those who say it really doesn't matter at all, but since you were asking and seemed like you wanted to do a "correct" job.

 

Just like mom used to make

 

OP this is pretty much impossible to screw up. Go to the store and buy some

$28 75w-90 Synthetic Gear Lube - 1 Quart (Pack of 2)

75w-90.

You will never be able to measure or quantify a difference between 75w-90 and 75w-85

 

Unless he got the info direct from whoever makes this for Toyota, GL5 doesn't make sense but maybe it is. Good luck finding aftermarket 75w GL5 oil though.

 

Car care nut is a master tech on YouTube. Dude has absolute baller info on Toyota maintenance that’s where I heard using GL-5 in the t-case. He also said throw

$28 75W-90 Synthetic Gear Lube - 1 Quart (Pack of 2)

75W-90 in everything and you should be good.

Some people on this thread said GL-4.

My owners manual did not specify a GL rating.

Due to all this conflicting information I decided the best route was to get the OEM stuff for the t-case and rest easy.

 

gl5 for the diffs
gl4 tcase (brass syncos)

I run Mobile1 delvac 75-90 diffs (if LS additive is not required)
redline 70-75 tcase
been doing this for 10+ years

 

Same, the Valvoline squeeze pouches make it easy.