Oil Change

I ran out and picked up 8 qt.s of Royal Purple 75w90 gear oil. I want to change out rear/front diff, manual transmission and transfer case. Could someone just verify for me that it is okay to use 75w90 in the rear diff when the manual says 80w90. According to the manual 75w90 works everywhere even the 6speed tranny?
Thanks
v6 trd off road.

 

I have always prefered a GL-4 (not Gl-5) rated manual transmission oil. The Gl-4 rating has different additives and basicaly is less slippery. GL-5 (your standard differential oil) is desigened for a hypoid gear set and not really for a manual transmission. Your sincros will work properly with the correct oil. Personally I have always run Redline MT-90 with great results.

**I know the manual says you can use either GL-4 or GL-5, I am just speaking from personal experience.

 

X2 on the MT-90!!

 

X3 on the MT90!!! Hated M1 75-90 in my 4runner trans. Always grinded 2nd.