[Tannero]

Hi everyone. I have a 2018 SS. Rear end had some rubbing noises and dealer flushed and changed fluid.

Improved some but now tire is wearing quick on right rear and squealing once in a while on right turns.

Took it in, they replaced one link they said was loose but no improvement. Any ideas?

Will take it back in but really want this fixed before I put new tires on again.

No grinding sounds? Just tight and needs constant fluid changes? Only has 20k miles on it.

[Joshinator99]

Originally Posted by Tannero

Hi everyone. I have a 2018 SS. Rear end had some rubbing noises and dealer flushed and changed fluid.

Improved some but now tire is wearing quick on right rear and squealing once in a while on right turns.

Took it in, they replaced one link they said was loose but no improvement. Any ideas?

Will take it back in but really want this fixed before I put new tires on again.

No grinding sounds? Just tight and needs constant fluid changes? Only has 20k miles on it.

If it’s a GM dealership you’d think they would have used the right fluid, but I trust them as far as I can throw them.

If that was your first time changing the diff fluid then that fluid was pretty cruddy I’d guess. I’d probably change that fluid again. They have to use a fluid with a friction modifier which the OEM fluid has. I’ve been using Red Line synthetic 75W-90 for years in mine for what it’s worth. But the differential should not be locking up like that.

[Tannero]

Originally Posted by Joshinator99

If it’s a GM dealership you’d think they would have used the right fluid, but I trust them as far as I can throw them.

If that was your first time changing the diff fluid then that fluid was pretty cruddy I’d guess. I’d probably change that fluid again. They have to use a fluid with a friction modifier which the OEM fluid has. I’ve been using Red Line synthetic 75W-90 for years in mine for what it’s worth. But the differential should not be locking up like that.

Thanks for the reply! Yea, was pretty disappointed a GM dealer can't fix it. I have to think it's common and others have experienced it? I'm hoping it's just fluid (again) - was changed and flushed at like 7K miles, now again at 24K I think. Pissed me off when they put a link in it, was like $700 and that hasn't done a thing. Going to go back, ensure I have a well trained guy working on the drivetrain, hopefully they listen.

[dmcmahan60]

I am going to say if it keeps needing the diff fluid changed then there is a possibility the differential is on it way out. I bought my car used with 11,000 miles on it and every time I changed the fluid there was more and more metal particles in it and black as tar I beat on it a few times at the drag strip so it was my fault also that it eventually failed. One day it popped making a right hand turn and from that point on when you let off the throttle the gear whining was horrendous:( Don't want to freak you out but that is what happened to me.

[KingLT1]

Agree with all mentioned above. These diffs are very sensitive to the type of fluid used. I could only get mine to stop making a "groaning" noise on turns with GM fluid and adding the posi additive. Even at that when it gets below 50 degrees out it still makes a slight noise on the first couple turns then it's dead silent. I consider this to be "Normal" for these rear ends based on research and some performance shops I have talked too.

So I would try changing it yourself with GM fluid / additive first(it's super easy), and if it doesn't get better, you will likely need to replace the diff.

[Tannero]

Originally Posted by KingLT1

Agree with all mentioned above. These diffs are very sensitive to the type of fluid used. I could only get mine to stop making a "groaning" noise on turns with GM fluid and adding the posi additive. Even at that when it gets below 50 degrees out it still makes a slight noise on the first couple turns then it's dead silent. I consider this to be "Normal" for these rear ends based on research and some performance shops I have talked too.

So I would try changing it yourself with GM fluid / additive first(it's super easy), and if it doesn't get better, you will likely need to replace the diff.

Thanks a bunch for the reply. I think I am going to take your advise - I'll research the GM fluid and additive to have and buy a little extra fluid, flush it good, change it - see how it goes. It wore the hell out of the right rear tire pretty quick compared to the left and now started squealing a little sometimes so changing the fluid to help the rear end and cut down on tire wear as well. If you have the name of the additive handy, would love to have the name so I can go get the additive and fluid. Haven't changed rear end fluid before but pretty handy, figure it should be as easy as pulling the top and bottom plugs if that's how it's setup, let it drain - put the bottom back in - fill to what ever level they spec, right? I'll hunt on YouTube, probably a video out there. Again, appreciate the help. Glad to hear others have that sort of growl when it's cold. Pretty warm up here in NY still but maybe just changing the fluid every 10-15K miles until it stops this locking.

[OB0001]

Originally Posted by Tannero

Thanks a bunch for the reply. I think I am going to take your advise - I'll research the GM fluid and additive to have and buy a little extra fluid, flush it good, change it - see how it goes. It wore the hell out of the right rear tire pretty quick compared to the left and now started squealing a little sometimes so changing the fluid to help the rear end and cut down on tire wear as well. If you have the name of the additive handy, would love to have the name so I can go get the additive and fluid. Haven't changed rear end fluid before but pretty handy, figure it should be as easy as pulling the top and bottom plugs if that's how it's setup, let it drain - put the bottom back in - fill to what ever level they spec, right? I'll hunt on YouTube, probably a video out there. Again, appreciate the help. Glad to hear others have that sort of growl when it's cold. Pretty warm up here in NY still but maybe just changing the fluid every 10-15K miles until it stops this locking.

Use ACDelco GM Original Equipment 10-4034 Dexron LS 75W-90 Gear Oil it already has the slip additive in it. I still have the GM whale oil slip additive bottles.

[p47dman]

Just did mine the other night, less than 10,000. Fluid clear, no metal on either plug. Drove it at 20 degrees outside. No noise, used GM OEM fluid.