1991 FJ80 Transfer Case and Differential Gear Oil Verification

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Feb 16, 2013
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Location
Kalamazoo Michigan
I’m sure the horse has been beaten dead on this one but I want to make sure I have this correct.
I have searched but seen mostly 93's and older listed.

I have a 1991 Fj80. Is this correct, I can use Mobil 1 Synthetic Gear Lubricant LS 104361 (75w -90) in my Transfer Case and Differentials. Also if I’m correct the 1991 Fj80 has Open Diffs but its safe to use Limited Slip gear oil in them?

FSM Calls For
Transfer case API GL-4 or GL-5 75w-90
Differentials API Gl-5 Hypoid Gear oil 80W -90

Thanks
 
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flintknapper

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May 22, 2004
Messages
10,686
Location
Deep East Texas
I’m sure the horse has been beaten dead on this one but I want to make sure I have this correct.
I have searched but seen mostly 93's and older listed.

I have a 1991 Fj80. Is this correct, I can use Mobil 1 Synthetic Gear Lubricant LS 104361 (75w -90) in my Transfer Case and Differentials. Also if I’m correct the 1991 Fj80 has Open Diffs but its safe to use Limited Slip gear oil in them?

FSM Calls For
Transfer case API GL-4 or GL-5 75w-90
Differentials API Gl-5 Hypoid Gear oil 80W -90

Thanks


The Mobil 1 product you cite has an API rating equal to or greater than called for in the FSM. (GL-5).


The limited slip aspect is nothing more than friction modifiers...which makes no difference in your differential.

The viscosity (lube weight rating) has no relationship to the API rating....simply use what is recommended or is appropriate for your climate. The API ratings themselves ARE important as GL-5 has approximately twice the EP additives that GL-4 does (Sulphur/Phosphorus).

Not an issue in our application...but you wouldn't want to use a GL-5 rated product where it would be in contact with Bronze or Copper components....since it is aggressive towards them.
 

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