Joining the rear diff club

[Displayhawk]

Sounds like a very common factory defect that's going to hit a lot of us. Wonder if they'll extend the warranty for this issue?

I bought my 2019 SB earlier this year with about 11,500 miles on it. I put about 1 oz. of Motorkote in the rear differential and about 5/8 oz. in the PTU. I drove it for about 500 miles and then pulled about 4 oz. of gear oil out, and added 4 oz. of LubeGard Differential treatment to each. The car now has 17,000+ miles on it, and there is no noises and runs smooth as silk. I even noticed a slight increase in gas mileage. So hoping this will prolong the life of both units.

 

[94cruiser]

A video of the hum noise can be found here:

 

[danzig997]

I bought my 2019 SB earlier this year with about 11,500 miles on it. I put about 1 oz. of Motorkote in the rear differential and about 5/8 oz. in the PTU. I drove it for about 500 miles and then pulled about 4 oz. of gear oil out, and added 4 oz. of LubeGard Differential treatment to each. The car now has 17,000+ miles on it, and there is no noises and runs smooth as silk. I even noticed a slight increase in gas mileage. So hoping this will prolong the life of both units.

Did you use this product?



Or this one ?



Did you use syringe like this?

 

[TourREX owner]

the one picture indicates it is for manual transmissions. Our Buick Tour X AWD is not manual systems When my rear differential started to groan when turning right, they never said to have added anything. They ordered the parts and replaced the system.

 

[danzig997]

the one picture indicates it is for manual transmissions. Our Buick Tour X AWD is not manual systems When my rear differential started to groan when turning right, they never said to have added anything. They ordered the parts and replaced the system.

Displayhawk stated "I put about 1 oz. of Motorkote in the rear differential and about 5/8 oz. in the PTU. I drove it for about 500 miles and then pulled about 4 oz. of gear oil out, and added 4 oz. of LubeGard Differential treatment to each. The car now has 17,000+ miles on it, and there is no noises and runs smooth as silk. I even noticed a slight increase in gas mileage. So hoping this will prolong the life of both units. "

 

[saab93driver]

I don't know if I'm joining the failed differential club but I'm joining the leaking diff club. No drips on the driveway but I smelled hypoid oil when fueling up returning from my last road trip. I looked underneath to see some oil film on the housing and surrounding areas. So far I don't have any strange noises. Dealer appointment next week to take a look at it. Just under 65K miles at this point so luckily should still fall under PT warranty.

 

[saab93driver]

I don't know if I'm joining the failed differential club but I'm joining the leaking diff club. No drips on the driveway but I smelled hypoid oil when fueling up returning from my last road trip. I looked underneath to see some oil film on the housing and surrounding areas. So far I don't have any strange noises. Dealer appointment next week to take a look at it. Just under 65K miles at this point so luckily should still fall under PT warranty.

Dealer ordered new differential, said should take about a week to get.

 

[mymaestro]

Joined the rear diff club this week. Covered under warranty with almost 53000 miles on it.
The dealer diagnosed the problem Monday, found faulty diff and leaky front power unit seal, plus a broken strut bushing. Parts arrived Friday, and the job was done the following Monday morning.
They covered the diff and front case seal under warranty, but it cost $400 to fix the strut bushing.

 

[danzig997]

I wonder where TourX GKN Twinster is made? definitely not in England.


The Range Rover Evoque, Ford Focus RS, Audi RS Q3, and other GKN-equipped

 

[TourREX owner]

I had to have my rear differential and drive line replaced about 17k miles The roaring when turning right issue. I am now at 36k and no more problems but have more miles on second differential than the first one.

 

[Greeno]

I had similar sound, ended up being a wheel bearing.

 

[RSE]

I took 2019 Sportback (28k) in for our state safety inspection, and asked them to look at the rear diff, as it has a oil seep at the axle seal. It wasn't bad enough to be considered a leak, but they did see an oil leak at the engine timing cover, and ordered parts.

 

[94cruiser]

Here we go.

Last several days I hear a very faint hum sound at what appears to be 30.5 mph. When I set the DIC to display MPH I can hear it at 30-31.
If I shift it to "manual" one gear down (to I believe 5th gear), I can hear it too. If I shift to 4th I can not hear it, and I suspect the engine noise is overpowering it.

This happens when driving forward.

I went under the car and it is 100% not clean. I can't pinpoint where the source is, but a large area of the chassis is coated with dirt.

The most I can see is what was forming on the bottom of the black bolt to what looks to me as one of the mounts on the driver side.
Attached are some photos.
Can you help?

 

[94cruiser]

Here we go.

Last several days I hear a very faint hum sound at what appears to be 30.5 mph. When I set the DIC to display MPH I can hear it at 30-31.
If I shift it to "manual" one gear down (to I believe 5th gear), I can hear it too. If I shift to 4th I can not hear it, and I suspect the engine noise is overpowering it.

This happens when driving forward.

I went under the car and it is 100% not clean. I can't pinpoint where the source is, but a large area of the chassis is coated with dirt.

The most I can see is what was forming on the bottom of the black bolt to what looks to me as one of the mounts on the driver side.
Attached are some photos.
Can you help?

Several days ago, as I was driving home in fairly heavy traffic all of a sudden smelled heavy presence of smell, like s locked up brake pad. This smell lasted for several blocks. I should have taken a turn and then get out of the car and try to smell it again, but I failed to do that.

Can it be related, or just a coincidence?
I wanted to open up the drain hole and smell the fluid, but the axle has color markings on all the bolts and don't want any hassles.

This rear end has been replaced by the dealer less than a year ago.

 

[Greeno]

I just found this forum. I have been dealing with a noisy differential on a 2018 TourX since it reached 22,000 miles (I took possession in March 2019). On the first dealer visit, I was told it is "normal". Returned to the dealer again around 50,000 miles and the noise had become even more noticeable upon turning left or right, accelerating, and climbing any grade. This time the dealer acknowledged the problem and changed the "fluids". This did little to solve the problem. I returned to the dealer again last week and they are back to denying the problem and told me the differential is no longer covered under warranty (>70,000 miles). A replacement was quoted at $3500. Clearly, this part is defective and the dealer/GM refuses to accept the responsibility. This is the first GM vehicle I have owned since 1989 and now the last. I remember why I stopped...

Browsing this thread, typically isn't it customary to change diff fluids on all vehicles around 25K? I know you can wait longer but these units I would assume are pretty rough on fluid with all the clutch action or what not back there. Knock on wood mines been good, at 51K now, purchased at 37K. Changed fluids in diff and transmission after an epic snow storm that required a few rocking events. Also had a clunk that turned out to be the previous owner put the wrong brake pads on, that was a weird one to track down! Wheel bearing needed replacing too. Driveline silenced right up after that (id imagine a dragging wheel bearing not the best for the AWD system either).

 

[94cruiser]

Had a leak from the diff and the driveshaft seal was replaced.
All nice for a long time.

Take it in for rear diff service several thousand miles before it’s due…
Shortly after have whine when turning.

Get the diff replaced at the dealer.
Less than a year later, hear humm at specific vehicle speed.

Check under the car, and see road grime residue all over the rear.
Calling the dealer tomorrow.

 

[danzig997]

I bought my 2019 SB earlier this year with about 11,500 miles on it. I put about 1 oz. of Motorkote in the rear differential and about 5/8 oz. in the PTU. I drove it for about 500 miles and then pulled about 4 oz. of gear oil out, and added 4 oz. of LubeGard Differential treatment to each. The car now has 17,000+ miles on it, and there is no noises and runs smooth as silk. I even noticed a slight increase in gas mileage. So hoping this will prolong the life of both units.

@Displayhawk what is the update on your Differential treatment since September 2022? Any issues?

Which type of LubeGard Differential treatment did you use?

 

[94cruiser]

Long story short.
My car had the rear differential replaced two times now.

 

[burgandy25]

Thought it best to update this thread as it's probably the longest thread related to Diff issues for the 2018+ Regal platform.

Our Regal GS has the diff chatter and leak, had the unfortunate discovery that the diff is discontinued:

P/n: 84535725

I hope there is a new P/n that takes this place eventually. Currently, according to dealership and every parts websites is that its "discontinued" and unable to be ordered. Luckly there is NOS for this according to my dealership. However, for a vehicle that still has warranty it's a little shocking to see that parts are discontinued with no replacement WHILE still being covered by GM (albeit for only a short period longer).

Just a warning, that if you have this issue and have been sitting on getting it looked at, maybe you might need to jump on bringing it into the dealership to try and get it resolved before warranty expires, or worse, parts are unobtainable.

I hope this is only a temporary parts shortage and not the end of the line for a diff replacement.

 

[saab93driver]

Thought it best to update this thread as it's probably the longest thread related to Diff issues for the 2018+ Regal platform.

Our Regal GS has the diff chatter and leak, had the unfortunate discovery that the diff is discontinued:

P/n: 84535725

I hope there is a new P/n that takes this place eventually. Currently, according to dealership and every parts websites is that its "discontinued" and unable to be ordered. Luckly there is NOS for this according to my dealership. However, for a vehicle that still has warranty it's a little shocking to see that parts are discontinued with no replacement WHILE still being covered by GM (albeit for only a short period longer).

Just a warning, that if you have this issue and have been sitting on getting it looked at, maybe you might need to jump on bringing it into the dealership to try and get it resolved before warranty expires, or worse, parts are unobtainable.

I hope this is only a temporary parts shortage and not the end of the line for a diff replacement.

When mine was replaced, I think about 1.5 years ago, the part number on the paperwork that dealer used was listed as also fitting the AWD XT4 Cadillac which is still in production so maybe there is some hope (and maybe an improved part).