Diff oil debate

Octanejunkie

Just another jagoff with a 4x4
Joined
Nov 2, 2018
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I read a lot of conflicting information about diff oils for our rigs. Most printed pieces say 80w 90. The passenger axle extension tube on the 7.5 reverse clamshell diff has a sticker that says 75w90 and ECGS says to run 85w140 in everything they build - as did Aussie Locker when I installed one of those years ago. Then there's the conventional vs synthetic and GL4 vs GL5 conundrum.

I'm planning on keeping it easy and running conventional 85w140 GL5 in both diffs. Any reason not to?
 

Stairgod

Two bad decisions away from buying a bulldozer
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Apr 22, 2019
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Nope. Just run dino oil.
Has better cling and cushioning than synthetic.
Pretty much ever diff builder swears by dino oil.
Trust the guys that build/fix shit rather than engineers or salesman
 
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I read a lot of conflicting information about diff oils for our rigs. Most printed pieces say 80w 90. The passenger axle extension tube on the 7.5 reverse clamshell diff has a sticker that says 75w90 and ECGS says to run 85w140 in everything they build - as did Aussie Locker when I installed one of those years ago. Then there's the conventional vs synthetic and GL4 vs GL5 conundrum.

I'm planning on keeping it easy and running conventional 85w140 GL5 in both diffs. Any reason not to?
Id
Nope. Just run dino oil.
Has better cling and cushioning than synthetic.
Pretty much ever diff builder swears by dino oil.
Trust the guys that build/fix shit rather than engineers or salesman
I'd also trust engineers, but to an extent ;)

A lot of new synthetic gear oils that (let say) Toyota uses, are supposed to be lighter and have/give less resistance, thus better highway fuel economy. They do whatever they can to meet the epa or whatever guidelines.
Just something to keep in mind, for "when in doubt" times.
 
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I'm running 85w-140 conventional for both mine. They are ECGS diff's. No issues. Change the fluid as needed you'll be good.
 

4runner DOA

Hold my beer
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Nope. Just run dino oil.
Has better cling and cushioning than synthetic.
Pretty much ever diff builder swears by dino oil.
Trust the guys that build/fix shit rather than engineers or salesman

This.

Edit: I still use synthetic in my transfer case. From what I read the 85-140 is too thick for it. Diffs get the 85-140.
 
Last edited:

Stairgod

Two bad decisions away from buying a bulldozer
Joined
Apr 22, 2019
Messages
2,438
This.

Edit: I still use synthetic in my transfer case. From what I read the 85-140 is too thick for it. Diffs get the 85-140.
T cases is a whole different matter.
Even in a gear driven case the gears don't see the same load and the mesh is completely different.
I am definitely a synthetic fan boy for everything but diffs
 
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