[CruzySS]

Took my 2016 A8 in for the issue. They looked up the service bulletin, changed the fluid under warranty and I was on my way. No questions asked.

[Chutzpah]

Originally Posted by TDX2000

I figured it's time to share my groan story with everyone. I first had the groan start about a month after I bought the car. I took it to one dealer and they tried to tell me it was the brakes. I didn't waste time trying to argue with them. I just took it to another dealer who has been great. When I took it to them I had already called GM support and opened a case with them. I gave the case number to the service guy and they did the rear diff fluid change and figure eights. That worked for about a month (maybe). I took it back in and they spoke with GM. GM authorized a rear diff carrier replace. They replaced the carrier the end of March. I have not had the groan until about 2 weeks ago. I took it back to the dealership. They heard the grown and had a GM tech come look at the car. He told them it was normal. The dealership asked me to come pickup my car. At this point I called GM and opened another case with them as if this was a "normal" behavior, they would not have a SB on it nor would they have replaced the rear diff carrier. I should hear back on this case from GM tomorrow. In total the car has been seen and documented for this issue 4 times now. I had to also take the car in for an issue with some sort of "vibration or chatter" when the car is warm and under slight acceleration. The dealership flushed the transmission fluid and told me to put 200 miles on the car. I have since put about 500 miles on the car and the chatter has not returned. At this point I am very concerned about the rear diff and transmission issues I have been having. I love the car but I am not willing to except this as normal operational behavior. I would not like to lemon law it, so I hope GM will step up and figure out what is causing this and fix it. My advice to anyone going through this BS is to find a good dealership and don't get mad at them. They usually can only do what GM authorizes. So put the pressure on GM. So far this approach has worked well for me.

Very reasonable response explaining your issues. As an fyi, changed my fluid at 3500 miles (it was groaning just a bit and felt like binding first turn of morning) Once changed, groaning / binding improved by 75%. Had a ton of cars, but never one (till now) with rear end noises / binding.

[Burly]

My car is getting its second diff fluid change tomorrow. They did the first about a month ago, I put 800 miles on it, and iwas still groaning. But the I would say the groan was 75% of what is was. Service manager said they may have not gotten all the original fluid out on the first fluid change...

[soloknight6]

Never had the groan. Did a diff fluid swap a few days ago @ ~13k miles. Fluid was SILVER, and stunk to high heaven.

[keon718nyc]

Going on 2 years and still got the groan after 2 diff fluid changes. I gave up on it... I will avoid the dealer at all costs unless its minor which to me this isnt.

[wvyankee2]

2017 4 Turbo/6 Man . I understand that I have the limited slip rear diff. Turning left mostly but right also I have the groan. Seems worse when cold.

[Rock-It Man]

Diff groan was much discussed in Gen5 as well.

I had some groan and got the oil changed. The groan diminished but on cold starts, sharp turns particularly in reverse are not silent. It's the nature of the limited slip to make some noise as the discs are slipping. My 2010 now has about 64,000 and the slight groan hasn't gotten any worse. The limited slip does its job when mashing the gas, too.

I had a rental jeep once that had obviously had its diff oil replaced with the wrong stuff. This was in Costa Rica. When you backing this car up while turning, it sounded almost like a collision as the diff grabbed and then released. That would be a problem!

[killervette666]

For what it's worth I read up on this issue shortly after buying my 2017 1SS and had my dealership change my oil and diff fluid at 500 miles. No groan at all. I would recommend an early diff fluid change (even if the service tech does look at you like crazy).

[Reaper333]

Ive had my differential fluid changed out a month ago. Still had the groaning. Two nights ago the differential took a dump on me and left me stranded in the middle of the night. I had it towed into the dealer that night. Next day they called me and confirmed that the differential was toast and they ordered a full assembly to be replaced under warranty. So, my advice to anyone with this issue is to keep taking it in because at some point it will fail. I took my 16 2ss in at least four times for this issue. Was told over and over that it was normal and that even with the fluid changes at some point the noise would come back. Very disappointed. Hopefully this will take care of the issue for me. Will see what happens Friday.

[suzook]

Originally Posted by Reaper333

Ive had my differential fluid changed out a month ago. Still had the groaning. Two nights ago the differential took a dump on me and left me stranded in the middle of the night. I had it towed into the dealer that night. Next day they called me and confirmed that the differential was toast and they ordered a full assembly to be replaced under warranty. So, my advice to anyone with this issue is to keep taking it in because at some point it will fail. I took my 16 2ss in at least four times for this issue. Was told over and over that it was normal and that even with the fluid changes at some point the noise would come back. Very disappointed. Hopefully this will take care of the issue for me. Will see what happens Friday.

Why waste our time taking in it, when they don't fix it. I had mine in 3 times. They keep telling me it's normal. Yeah, ok, can't wait till my lease is up, see you GM! I'm done with this crap.

[Reaper333]

Originally Posted by suzook

Why waste our time taking in it, when they don't fix it. I had mine in 3 times. They keep telling me it's normal. Yeah, ok, can't wait till my lease is up, see you GM! I'm done with this crap.

I cant say I blame you. Its very irritating that GM doesn't stand behind their product. I'm just hoping that this will fix my issue with it. But question is what will break next.

[Burly]

I am on third flush and started groaning again but only on cold start. I give up.

[Reaper333]

I just got a call from the dealer. They are also replacing the axles. Must have been really bad. Sigh sucks

[keon718nyc]

I had 2 flushes done last year and said fuk it, when my lease is up they can deal with the noise. I can't waste any more time trying to get something fixed that won't... Now that the colder weather is here the noise is coming back in full force. Good job GM!!!