'16 Camaro SS diff fluid help

[stook2001]

Hi Everyone,
Hoping someone might be able to provide some assistance. There are MANY owners reporting groaning issues from the limited slip rear diff on the 16+ Camaro SS. This issue seems to crop up for most people within a few thousand miles. It happens in colder weather only (below 50 deg F, give or take) and happens only for the first few turns when the vehicle is cold.

GMs "solution" for this has been to advise dealers to drain and refill the fluid with their OEM limited slip gear oil. Owners are reporting that this approach improves the issue for a while but that it generally comes back. Some owners have also received new diffs and many of those replacement parts also end up with the same issue.

From researching here on BITOG, I believe the OEM oil is this one here: Link

I took the liberty to build a google docs spreadsheet comparing the published specs for the OEM fluid and compared it against the specs that are available for aftermarket options. As you can see, I was looking at several fluids marketed to the commercial semi truck market since I am sure the diffs for these vehicles are expensive and reliability is critical. Not to mention, some of these trucks are running super long fluid change intervals, which I'd assume would require a very robust fluid.

At any rate, what I discovered seemed to be quite interesting. It appears that the OEM fluid that GM is using is rather substandard in terms of viscosity. The google docs sheet is here: google docs

I would appreciate any assistance that could be provided interpreting this data. Also, I realize this is a long shot, but I am trying to figure out the maker and more details about the diff in the car. This information does not seem to be readily available. The part number seems to be specific to the Camaro only based upon a part number search using GMPartsDirect. I realize that Eaton is one of the bigger OEMs for GM diffs. I have emailed them using their customer service webform to find out if they are the supplier but I have low expectations for hearing back from them with anything useful.

By the way, at the moment, I am leaning towards using Mobil Delvac 75w90. I have not decided which friction modifier to use.

thank you!

 

[danthaman1980]

Sounds a lot like the issue I ran into with my Quadrasteer several years ago. At around 75k, the rear end started GROANING fiercely. The OEM 'Quadrasteer Limited Slip' gear oil was the solution. Apparently the Quadrasteer limited slip rear end (basically a Dana 60 equipped with Trac-Lok) requires more friction modifier than normal LS gear oils are equipped with. The problem is, at the time nobody really knew how much more. I tried Amsoil SVG + 2/3 bottle of FM; didn't help. OEM fluid did the trick. Yes, it was expensive ($30/qt x 3 qts.). But it was worth it and in my case the OEM oil lasts ~75k-100k before the groaning starts up again. I've had to change it twice in ~228k miles and I'm probably approaching change #3.

TL;DR - Go with the OEM fluid, I've seen this happen with GM LSDs before.

 

[stook2001]

Originally Posted By: danthaman1980
Sounds a lot like the issue I ran into with my Quadrasteer several years ago. At around 75k, the rear end started GROANING fiercely. The OEM 'Quadrasteer Limited Slip' gear oil was the solution. Apparently the Quadrasteer limited slip rear end (basically a Dana 60 equipped with Trac-Lok) requires more friction modifier than normal LS gear oils are equipped with. The problem is, at the time nobody really knew how much more. I tried Amsoil SVG + 2/3 bottle of FM; didn't help. OEM fluid did the trick. Yes, it was expensive ($30/qt x 3 qts.). But it was worth it and in my case the OEM oil lasts ~75k-100k before the groaning starts up again. I've had to change it twice in ~228k miles and I'm probably approaching change #3.

TL;DR - Go with the OEM fluid, I've seen this happen with GM LSDs before.


I appreciate the reply. Keep in mind, this is happening with essentially brand new vehicles. My car, for instance, has less than 3,000 miles on it. The problem seems to start for most owners in the 1500-3000 mile time frame. I'm not disputing that it could be insufficient friction modifier. Well, actually, I AM kind of suspect of that idea if I am being totally honest. After a couple of miles of driving the noise disappears and there isnt any kind of weird binding. I'd expect binding with insufficient additive. The other important detail is that fluid swap with new OEM fluid seems to solve or improve the issue but only temporarily.

 

[Rat407]

I wonder what changed from earlier models. My 2013 Camaro SS is fine. I did change the fluid out at 500 miles to AMSOIL's Severe Gear 75w-90 and added 2.3oz of their slip lock as well. It has 12k miles on it and all is well.

 

[stook2001]

16+ is on a new platform. The drivetrain is different.

 

[RedOakRanch]

Sounds like the 8.8 IRS LS in my old Explorer. After 3 warranty fixes at the dealer I put in Amsoil SG 75w140 with the whole bottle of additive from Napa and never had an issue for the next 100k. I did rinse and repeat every 30k for good measure.

 

[zeng]

Originally Posted By: RedOakRanch
Sounds like the 8.8 IRS LS in my old Explorer. After 3 warranty fixes at the dealer I put in Amsoil SG 75w140 with the whole bottle of additive from Napa and never had an issue for the next 100k. I did rinse and repeat every 30k for good measure.

I would believe any xxW140 of higher KV@40*C is the way forward for OP .... whilst taking care of LS additives.

Probably 75W90 is the CAFE thing for OEM's corporate financial performance.

 

[stook2001]

Thanks for all the input. I found out some more information that I believe to be reliable but can't 100% confirm yet. The rear diff appears to be made by American Axle & Manufacturing. It is a 218mm clutch type limited slip diff. That's all I know.

I have the 75w90 delvac already on order. Trying to make an informed judgement on the limited slip additive.

 

[wtd]

What ever you choose to use, I would make sure it meets the warranty requirements for your car in case you need it in the future.

If you go to the forums for the Mustangs and Challengers, you also read about many rear end noises. I have a 2014 Mustang GT with the solid rear axle and even for my rear end design, you read many complaints about rear end noise.

I personally think that in this day and age these companies that make these rear ends just don't do a very good job of getting them set up correctly and probably use inferior parts to build them with. It's not like rear end design is really that new, even with IRS.

Wayne

 

[Harambe]

Maybe try using this stuff? It is probably premixed in your fluid already but maybe it needs more. Seems like it is designed for issues like yours.

https://www.amazon.com/ACDelco-10-4003-Limited-Lubricant-Additive/dp/B000QGMXSU

 

[stook2001]

thanks everyone, my issue is not chatter, I don't think. Anyway, I did decide to go with the delco friction modifier, which appears to be made by Lubrizol, judging by the msds. Ultimately, I couldn't figure out a logical way to decide which friction modifier to use. In the absence of any data to go on, I decide to try changing one thing at a time and just use the Delvac with the OEM friction modifier. If that fails, I might try the Ford friction modifier instead.