Joining the rear diff club

[fredzy]

Chalk mine up as in the club also, early 2018 build TourX Essence. Bought this past August with 80k miles, it had just been just traded in. The dealer did a ton of service on it just prior to sale which I considered a plus. All totally routine stuff except "change rear diff fluid" - I thought nothing of it at the time. Later I saw there was no diff fluid change in the scheduled maintenance for the car, and by then I had heard about this issue. I kept that in the back of my mind because the car made no noise or vibration.

700 mi or so into my ownership I began to notice a vibration seemingly coming from the back of the car when cruising at 55+ mph. I rotated the wheels around and it had no effect on where and how the vibration felt. At 1500 mi I brought the car to the dealership for my one free complimentary oil change (it expired after 90 days from purchase 🙄) and asked them for the detailed service record from when they changed that diff fluid. Sure enough, in the notes for the job was "intermittent noise when turning." Once it was on the lift they let me take a look and its clearly weeping. As am I now lol.

So I will check it every few months to get a feel for how fast its leaking out and keep it topped up. I've never heard any noise and I don't know if the vibration is related..🤞all I can do is keep it topped off and hope it behaves. I'll be checking the level for the first time tonight.

 

[quakerj]

Chalk mine up as in the club also, early 2018 build TourX Essence. Bought this past August with 80k miles, it had just been just traded in. The dealer did a ton of service on it just prior to sale which I considered a plus. All totally routine stuff except "change rear diff fluid" - I thought nothing of it at the time. Later I saw there was no diff fluid change in the scheduled maintenance for the car, and by then I had heard about this issue. I kept that in the back of my mind because the car made no noise or vibration.

700 mi or so into my ownership I began to notice a vibration seemingly coming from the back of the car when cruising at 55+ mph. I rotated the wheels around and it had no effect on where and how the vibration felt. At 1500 mi I brought the car to the dealership for my one free complimentary oil change (it expired after 90 days from purchase 🙄) and asked them for the detailed service record from when they changed that diff fluid. Sure enough, in the notes for the job was "intermittent noise when turning." Once it was on the lift they let me take a look and its clearly weeping. As am I now lol.

So I will check it every few months to get a feel for how fast its leaking out and keep it topped up. I've never heard any noise and I don't know if the vibration is related..🤞all I can do is keep it topped off and hope it behaves. I'll be checking the level for the first time tonight.

View attachment 47824

The level would be your only indication of whether the noise is fluid related. It could simply be the diff's time on this Earth is over. I don't really see anything amiss in the photo, in fact I can't see a leak of any kind. Slow "seeping" is normal per GM, but not if it's leaving drops on the driveway.

 

[fredzy]

The level would be your only indication of whether the noise is fluid related. It could simply be the diff's time on this Earth is over. I don't really see anything amiss in the photo, in fact I can't see a leak of any kind. Slow "seeping" is normal per GM, but not if it's leaving drops on the driveway.

In that picture above, all of the stuff to the left that looks like black spray paint is road grime wet with oil. See below the same area after a little cleaning, and also the other side for comparison with no evidence of oil wetness at all.

I got under it to check the level tonight and I'm glad to say that when I popped the fill plug the oil came dripping out. So its not leaving fast enough that I'll need to top up more than once or twice per year, I guess.

Cleaned up some of the gunk:


Other side bone dry and clean:

 

[quakerj]

In that picture above, all of the stuff to the left that looks like black spray paint is road grime wet with oil. See below the same area after a little cleaning, and also the other side for comparison with no evidence of oil wetness at all.

I got under it to check the level tonight and I'm glad to say that when I popped the fill plug the oil came dripping out. So its not leaving fast enough that I'll need to top up more than once or twice per year, I guess.

Cleaned up some of the gunk:
View attachment 47825

Other side bone dry and clean:
View attachment 47826

All I can see is thumbnails on this site for some reason. An actual leak would have visible oil that is slinging off onto surrounding areas and when bad it will begin leaving drips when the car sits. If it's just some oily grime around the seal and immediate area, it's "normal" (per GM) seepage.

Mine has black gunk around one of the axle seals. My fluid level is holding steady, so I just pop underneath there at least every oil change to monitor and it hasn't gotten any worse.

Is the car currently exhibiting failed differential symptoms? If not, just keep a close eye on that area and especially fluid level.

 

[fredzy]

All I can see is thumbnails on this site for some reason. An actual leak would have visible oil that is slinging off onto surrounding areas and when bad it will begin leaving drips when the car sits. If it's just some oily grime around the seal and immediate area, it's "normal" (per GM) seepage.

Mine has black gunk around one of the axle seals. My fluid level is holding steady, so I just pop underneath there at least every oil change to monitor and it hasn't gotten any worse.

Is the car currently exhibiting failed differential symptoms? If not, just keep a close eye on that area and especially fluid level.

My only possible symptom now might be vibration (can't verify the source.) Same as you, I'm hoping it stays happy as long as I keep it topped up.

 

[quakerj]

My only possible symptom now might be vibration (can't verify the source.) Same as you, I'm hoping it stays happy as long as I keep it topped up.

Vibration/noise while turning at slow-moderate speeds (clearly coming from rear) would be indicative of a rear diff failure. Just keep a close eye on it and post any updates.

 

[yukondon]

I agree, very easy to do. Even the transmission drain/fill is a fairly simple job if you read and follow the procedure.

You're a brave soul though, one of the first forum posts I read after buying the car in early 2023, was the story of a fella who changed their rear diff fluid out w/ some aftermarket stuff, and within 1K it grenaded. That was enough for me to stick with OEM. But as they say, correlation ≠ causation.

Tip on rear diff drain/refill...Removed the 10mm hex drive from my socket by punching it out from behind in the vise with a drfit. Now I could easily insert in the fill fitting and loosen with a 10mm wrench - no interference with the rear sway bar. Drained and filled with Dexron LS gear oil per spec. No more groaning from the rear diff. (70K miles)

 

[fredzy]

Tip on rear diff drain/refill...Removed the 10mm hex drive from my socket by punching it out from behind in the vise with a drfit. Now I could easily insert in the fill fitting and loosen with a 10mm wrench - no interference with the rear sway bar. Drained and filled with Dexron LS gear oil per spec. No more groaning from the rear diff. (70K miles)

Once I realized I had no proper tool on hand to get this thing off, I took a closer look at the plug and could see that it had been vice-gripped or maybe even pipe wrenched off in the past.

I decided to carry on that tradition and used vice grips for removal and re-installation 🤷‍♂️ fortunately I was able to get it off and then back on with a healthy dose of torque with no slipping or mangling of the plug, but I can not recommend this method to anyone.

 

[quakerj]

Tip on rear diff drain/refill...Removed the 10mm hex drive from my socket by punching it out from behind in the vise with a drfit. Now I could easily insert in the fill fitting and loosen with a 10mm wrench - no interference with the rear sway bar. Drained and filled with Dexron LS gear oil per spec. No more groaning from the rear diff. (70K miles)

I cut mine down with an angle grinder, which left about 3/8" of hex. It's an otherwise normal 3/8" drive socket and fits easily when using a breaker bar -- trying an actual ratchet may make it too tight. Trimming it down to ~3/8" makes it just as useful as before; I've never encountered a bolt yet that it won't bottom out in.

Once I realized I had no proper tool on hand to get this thing off, I took a closer look at the plug and could see that it had been vice-gripped or maybe even pipe wrenched off in the past.

I decided to carry on that tradition and used vice grips for removal and re-installation 🤷‍♂️ fortunately I was able to get it off and then back on with a healthy dose of torque with no slipping or mangling of the plug, but I can not recommend this method to anyone.

Well heck, at least you know someone has checked fluid and/or serviced it before! I would have never though of the pipe wrench idea. All's well that ends well!

 

[Displayhawk]

Well, add me to the rear differential replacement club! I took my 2019 Regal Sportback Essence to my local Buick dealership with 52,600+ miles on it. I took it in Wednesday morning hot and making the "moaning", rubbing or grabbing noise when turning everyone is describing. I called back today (Thursday afternoon) and was told that they were out test driving it. The rear differential needs to be replaced, and fortunately it is under warranty. They said the warranty runs out January 2nd, 2025. I didn't know about any time warranty. I thought it was just 70k miles. But glad it is being replaced under warranty. They said the new differential was from a different vendor, and that they haven't had any issues with the new differentials. They also said that the new differential comes with 24 month / 24k mile warranty. I can't believe they don't do a recall on this issue since it seems like a LOT of these cars are having problems. On a side note, I replaced the original rear differential gear oil at around 30k, so it leads me to believe this is a design issue.

 

[Crispy]

Sorry for your loss Displayhawk. I find this post very disheartening! I’m on this thread because we had a seal replaced under warranty at 15k. Since then, I have been maybe unrealistically thinking I am ahead of the game with that fluid change at 15k. Now at 60k on the 2018 TX.
Question… What is the actual failure? Do others here feel more frequent fluid changes can be a help against failure. It’s our only defense. I’m thinking about a fluid change asap after reading this. C.

 

[Displayhawk]

Sorry for your loss Displayhawk. I find this post very disheartening! I’m on this thread because we had a seal replaced under warranty at 15k. Since then, I have been maybe unrealistically thinking I am ahead of the game with that fluid change at 15k. Now at 60k on the 2018 TX.
Question… What is the actual failure? Do others here feel more frequent fluid changes can be a help against failure. It’s our only defense. I’m thinking about a fluid change asap after reading this. C.

I personally think it was either a bad design or inferior materials. I changed the gear oil several times, and it didn't seem to help.
FYI, I asked the dealer if the new differential would be better or last longer than the original, and he told me that it was from a different vendor. so hopefully that will be the difference.
BTW, the warranty on the new differential is 24 months / 24k miles. I was wondering if anybody who has had their rear differential replaced, has had any further problems? I am thinking of getting a beater car for short trips around town, and save my Sportback for longer / special trips. It's a great cruiser, and I really like driving it, but I don't want to constantly put money into it.

 

[quakerj]

I personally think it was either a bad design or inferior materials. I changed the gear oil several times, and it didn't seem to help.
FYI, I asked the dealer if the new differential would be better or last longer than the original, and he told me that it was from a different vendor. so hopefully that will be the difference.
BTW, the warranty on the new differential is 24 months / 24k miles. I was wondering if anybody who has had their rear differential replaced, has had any further problems? I am thinking of getting a beater car for short trips around town, and save my Sportback for longer / special trips. It's a great cruiser, and I really like driving it, but I don't want to constantly put money into it.

Different vendor? Do they mean manufacturer? I'm not sure how that can be since the GKN Twinster is such a unique design and was only equipped on a few different production cars-- some Land Rovers, Focus RS, a few others.

 

[saab93driver]

Different vendor? Do they mean manufacturer? I'm not sure how that can be since the GKN Twinster is such a unique design and was only equipped on a few different production cars-- some Land Rovers, Focus RS, a few others.

The part number has changed along the way, don't know it that means there was a design change to it to improve or fix something. Same part number fits Cadillac XT4 with AWD.

 

[quakerj]

The part number has changed along the way, don't know it that means there was a design change to it to improve or fix something. Same part number fits Cadillac XT4 with AWD.

I've noticed that as well. I have the new part number saved which is not the same as what is installed in the car.

I've contemplated purchasing one prophylacticly (sp?) just to have in the garage in case mine fails. I've found them just over a grand (new part #), which I think is a great deal for a part that could potentially be non-existent (in US) in the coming years. If I never use it, there's sure to be someone looking for it.

When I programmed my Tour-X with the most recent updates via GM SPS, there was a new calibration for the rear differential module. I forget the exact terminology, but it mentioned something about rear-diff noise and it had a newer calibration. I installed it like I did the other updates. I'm curious if there's something to that newer update that my early-2018 build didn't have, and whether it affects rear diff failure rates.

Edit: Seems the proceeding part numbers are: 84894045, 86821895, 84672963. Newest product being 86506324. Please correct me if I'm wrong.

 

[Displayhawk]

I've noticed that as well. I have the new part number saved which is not the same as what is installed in the car.

I've contemplated purchasing one prophylacticly (sp?) just to have in the garage in case mine fails. I've found them just over a grand (new part #), which I think is a great deal for a part that could potentially be non-existent (in US) in the coming years. If I never use it, there's sure to be someone looking for it.

When I programmed my Tour-X with the most recent updates via GM SPS, there was a new calibration for the rear differential module. I forget the exact terminology, but it mentioned something about rear-diff noise and it had a newer calibration. I installed it like I did the other updates. I'm curious if there's something to that newer update that my early-2018 build didn't have, and whether it affects rear diff failure rates.

Edit: Seems the proceeding part numbers are: 84894045, 86821895, 84672963. Newest product being 86506324. Please correct me if I'm wrong.

THANKS for the info! I am finally supposed to get my car back tomorrow. I am going to ask if it will help to change the gear oil every year? The gear oil is only about $20 - 30, and it is really quick and easy to do.

 

[Gambrinus]

Just replaced mine. I bought my 2018 Tour-X new 6+ years ago. The Diff lasted 132,000 miles. This one should last me (I'm hoping) another 100k plus. I've always hoped to get 250k miles out of this car.

 

[2018 TourX in Texas]

I just read every post - all 300 ish / 15 page thread. Whew !

Q: Has anyone tried just adding more Friction Modifier Limited Slip Additive ?

It's said this will quiet noisy diffs and internal clutch packs.

Reason I ask is there are several posts where guys got rid of the offending "growling diff while turning at low speeds" after refilling with the proper GM LS - limited slip - Gear Lube.

I had earlier replenished my rear diff using this GM LS Diff Fluid so fluid is very fresh but I wondered if maybe just maybe the GM Lube didn't contain enough of the LS additive - which IS sold separately in a 4 oz bottle.

I figure I have little to lose.

It's definitely beginning to make the dreaded noise - not horrible loud but definitely there - louder turning one direction vs the other, on smooth pavement maneuvering to park it's evident but not loud.

But totally silent going forward regardless of speed - (So far !).

So, short of going into dealer for new diff en toto I lll give the GM LS additive a go.

And post back my results.

Btw, I see the new "Differential Carrier Assembly" that also fits the Cadillac XT4 - it's about $1400 from several sources.

Why are Buick dealers ending up charging $3000 + for this job - surely it can't be $1600 labor to install ?!?

Thx David in Texas

 

[gmtech 2019]

I have a 2019 Lacrosse AWD. Does it use this same rear assembly?

 

[PrincipalDan]

I just read every post - all 300 ish / 15 page thread. Whew !

Q: Has anyone tried just adding more Friction Modifier Limited Slip Additive ?

It's said this will quiet noisy diffs and internal clutch packs.

Reason I ask is there are several posts where guys got rid of the offending "growling diff while turning at low speeds" after refilling with the proper GM LS - limited slip - Gear Lube.

I had earlier replenished my rear diff using this GM LS Diff Fluid so fluid is very fresh but I wondered if maybe just maybe the GM Lube didn't contain enough of the LS additive - which IS sold separately in a 4 oz bottle.

I figure I have little to lose.

It's definitely beginning to make the dreaded noise - not horrible loud but definitely there - louder turning one direction vs the other, on smooth pavement maneuvering to park it's evident but not loud.

But totally silent going forward regardless of speed - (So far !).

So, short of going into dealer for new diff en toto I lll give the GM LS additive a go.

And post back my results.

Btw, I see the new "Differential Carrier Assembly" that also fits the Cadillac XT4 - it's about $1400 from several sources.

Why are Buick dealers ending up charging $3000 + for this job - surely it can't be $1600 labor to install ?!?

Thx David in Texas

As far as the labor... Certainly there are all sorts of fees in the price too. Tax, cost of the fluid to fill the new unit... Dealership labor rates are what? $150 to 200 an hour? For a dealer to install a $1500 to $2000 part a grand total of $3000 doesn't shock me.

I love my TourX but I'm likely to dump it when I've got it paid off. I enjoy the car but not $3000 of love to go to higher miles.