Differential fluid change question

[Btmbass]

Hello everyone,

I want to do change the fluid in the front and rear diffs and the transfer case. I've read up on this a bit and have read differences on if adding LSD fluid is necessary or not. From what I'm read if my 98 tahoe has a G80 axle I do not need to add LSD fluid, just normal diff fluid. I looked up my RPO codes but all I can find with that number is the gear ratio.

How can I find out 100% what fluid is needed and how much?

 

[lesterl]

What G codes do you have?

 

[Btmbass]

Thanks for the reply it is GU6. I looked at the rear diff to see if I could find any identification but it is scary looking. The cover and bolts are beyond rusted. a chunk of a bolt head flaked off just from me trying to clean it up a bit. I don't think I'm going to risk having a bolt break off in the axle just to change the fluid.

 

[lesterl]

You have a standard 3:42 gear.... not a bad one to have for MPG's......

Is it causing you ANY issues? Noise/ whine/ chatter/ etc?

 

[Btmbass]

No issues. I just bought it a few months back so I have been trying to change out all the fluids so I can get a clean mike count on them. Thank you for the help!


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[MO Viet Vet]

Mile count, correct? Use a hand pump and go thru the fill hole and pull as much old fluid out as you can. Refill with correct fluid. Rig must have been in a state that uses salt in the winter.

 

[Btmbass]

I'm still not certain if this axle needs LSD additive or just the diff oil?


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[MO Viet Vet]

The G80 would be the code if you had it.

 

[Btmbass]

I don't see that code so it's an open diff that just takes standard 75-90w oil


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[MO Viet Vet]

Yes.

 

[Btmbass]

Thank you kindly!


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[MO Viet Vet]

If you are keeping the rig I would get that rear cover off. You may break some bolts and have to drill and re tap but I would want to see in there. Use a good penetrating fluid like Aero Kroil, the absolute best there is, and follow directions and open up and see if has any gear damage or any metal in there. Your call. You can get the Aero Kroil at ebay or other places. About $20 a can but there is none better.

 

[lesterl]

If you have trouble with a bolt, you could always heat it with a torch also......