Rear differential slipping/chattering after fluid change

[Mshawn]

On 9/13/2023 at 5:38 PM, parkermonte55 said:

Sounds like they did not add the posi trac additive. It is like a two or three ounce bottle. It will cause the diff to chatter without it.

Correct. Take it back and demand them to add the fiction modifier they were suppose to use. Al do you can go to parts and get p/n of the friction modifier. Then check your invoice and see if it was billed out to your truck. That still doesn’t mean he put it in there. Hope this helps. G80 has to have the friction modifier 

[txab]

1 hour ago, scole said:

How does the high end weight of a lubricant affect it's performance? How does a 75W90 behave compared to a 75W140 rear diff lube? I understand 140 is more viscous than 90 but in a multi-weight lube how do they behave?

Has the dealer flushed and swapped out the diff fluid yet?

[scole]

2 minutes ago, txab said:

Has the dealer flushed and swapped out the diff fluid yet?

Yes, they drained and filled with the OEM lube. Just got it back yesterday but will post back after a week whether slipping/chatter gone. Their techs said they did not experience it but I've driven that truck nearly every day for over 6 years, 85k miles and I know how it drives.

[txab]

22 minutes ago, Mshawn said:

Correct. Take it back and demand them to add the fiction modifier they were suppose to use. Al do you can go to parts and get p/n of the friction modifier. Then check your invoice and see if it was billed out to your truck. That still doesn’t mean he put it in there. Hope this helps. G80 has to have the friction modifier 

G80's DO NOT require any friction modifier additives. It's stated throughout this website, even in this thread by a current GM Tech

[scole]

40 minutes ago, Mshawn said:

Correct. Take it back and demand them to add the fiction modifier they were suppose to use. Al do you can go to parts and get p/n of the friction modifier. Then check your invoice and see if it was billed out to your truck. That still doesn’t mean he put it in there. Hope this helps. G80 has to have the friction modifier 

The lube they put in it here does have the friction modifiers in it but as mentioned it's not supposed to. The G80 rear diff in this truck is the Eaton Locker, not limited slip. See the post about the Eaton service bulletin here

[Mshawn]

On 9/16/2023 at 8:52 PM, Mshawn said:

Correct. Take it back and demand them to add the fiction modifier they were suppose to use. Al do you can go to parts and get p/n of the friction modifier. Then check your invoice and see if it was billed out to your truck. That still doesn’t mean he put it in there. Hope this helps. G80 has to have the friction modifier 

LOL!