Transfer Case Oil

Joined
Apr 17, 2021
Messages
171
Location
Calgary, Alberta
When I search which oil to use for the transfer case most of the threads are 7-10 years old. I have searched in my area and the only gear oil I can find is blends i.e. 80w90 GL-5 etc. The FSM says SAE90 GL-4. In some of the old threads, there are comments that only GL-4 should be used in older transmission and transfer cases. I have a stock 1973 3 Speed with pto. Any guidance would be appreciated.
 

Skreddy

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Feb 3, 2020
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Stanwood, WA
Do you have a Carquest nearby? I’ve been using their house brand 90 wt GL-4. I think now it’s labeled as Fram.
 
Joined
Apr 17, 2021
Messages
171
Location
Calgary, Alberta
the GL-4 part is important....GL-5 will eat gold metal parts under the right conditions.
The issue that I'm having is most oils that any oils that have GL-4 listed also list GL-5. There is one example, Spirax S4 AX High Performance Axel & Differential Oil, 80W90, 20-L API GL-4, GL-5, API MT-1, SAE J2360. Would this work or should I keep looking for GL-4 only?

 
Joined
Jul 18, 2022
Messages
71
Location
Liberty, Kentucky
You will have a difficult time finding a GL-4 only lubricant at your local parts houses and suppliers. I recently had luck purchasing 90W GL-4 from StarFire Lubricants, I'm not sure if they have any left but I bought two 5 gallon buckets for about $50 each. If you don't care to pay $$$ you can always buy Redline MT-90 from Summit Racing or similar.
 
Joined
Dec 14, 2007
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SoCal
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forum.ih8mud.com
I don't know if Canada has it but some of us on this board are using this oil: PennGrade 1® Classic GL-4 Gear Oil SAE 80W-90 - Gear Lubricants - https://penngrade1.com/products/gear-lubricants/penngrade-1-classic-gl-4-gear-oil-sae-80w-90/

PG1_-MP-GL-4-GO-80W90_Qt.jpg
 

hobbes

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Feb 2, 2002
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SWFL
My local NAPA carries Sta-Lube GL-4 85w-90. Its on Amazon for a (somewhat) reasonable price. No idea if that helps in Alberta.

Amazon product
 
Joined
Jul 18, 2022
Messages
71
Location
Liberty, Kentucky
Doing some service work on my Kubota and was comparing hydraulic fluids. I stumbled across this...
Note: The Service Designation "GL-4" implies that it is yellow metal safe, saying both GL-4 and YM Safe is redundant. Since our trucks don't have hypoid gears in the T-case or Trans, Chevron 1000-THF should be a suitable transmission and transfer case lubricant.

gl4.JPG
 

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