[Sobak]

Originally Posted by Spaceme1117

As for what you should do, I don't know. You could do like others have said and change the fluid a couple of times and see if everything is okay. But if you do that, you will remove the proof of ATF in the system other than your receipt.

I suspect that the proof was removed yesterday when they realized their mistake and replaced it with the proper fluid. I fully believe that if I change it out it will be the correct fluid. The only evidence I have is the invoice that states "Part ATF Transmission Fluid Multi-Application - ATF"

Originally Posted by dmcmahan60

when I say be an A$$ I mean just talk to the manager and voice your concerns.

I plan to, right now they are dodging me so that tells me they know what they did and they understand that I’m calling BS on their explanation yesterday. I feel that they will not respond to e-mail, if they did do something wrong. I did drive the car yesterday and while there are some clunks and moaning sounds, the noise I heard on Sunday is gone. Plus, I always drive with the radio on so those clunks and moans might be part of the normal operation. I always had the moan when turning but I also learned on these forums that you should change your differential fluids quickly.

Originally Posted by Spaceme1117

And if you can, change fluids yourself.

Absolutely, I have a great garage setup, portable lift, tools, and lighting. I even have an A/C installed for those hot Texas summers, but I always got my fluid changed at a shop, it should have been easy to do and they have the resources and means to dispose of the used fluids. BUT, I learned my lesson and now I’m doing all my fluids myself, at least I’ll know it’s done correctly.

[UnknownJinX]

Originally Posted by 2SS Capt

Meh.... I'd say 75W-90 is a LOT thicker than 5W-30 (unless the 5W-30 was in a freezer for a VERY LONG while...) All of my other (4) cars run 5W-20, which looks like typical motor oil, the 75W-90 I put in my rear diff was QUITE thick compared to that... Any ATF I have ever poured has been thinner or at most, the thickness of 5W-20... 75W-90 is FAR thicker... I'd be very concerned...

I looked up again and 75W-90 gear oil is more like 10W-40 engine oil. So yeah, thick stuff.

For some cars, they tell you to run 10W-30 in the manual trans/diff in a pinch if the appropriate fluid is unavailable. Of course, you should change it out ASAP because as I mentioned, you are missing the appropriate additive packages.

Originally Posted by Jofu

Surprising the guy who made the change didn't notice the liquid he removed being very thick. You'd think he would have been like "Oh... Waaaaaiiiiiiit a minute"

Geoff

The colour should be the telltale sign, honestly. ATF has a very distinct crimson colour to it that no other fluids really have. That's assuming the person doing the work isn't colourblind.

Originally Posted by Sobak

Absolutely, I have a great garage setup, portable lift, tools, and lighting. I even have an A/C installed for those hot Texas summers, but I always got my fluid changed at a shop, it should have been easy to do and they have the resources and means to dispose of the used fluids. BUT, I learned my lesson and now I’m doing all my fluids myself, at least I’ll know it’s done correctly.

If oil change places don't take in your used car fluids, just go to the nearest landfill. They will take them in free of charge as long as you are not commercial.

[Sobak]

Hey guys, I wanted to update all of you. The shop called me back and basically told me what I thought all along, they put the wrong gear oil in the system. They blamed it on their software recommending the wrong oil, I find that hard to believe. This morning I put the car on the lift and drained the diff again, what came out was consistent in color and smell to Dexron 88862624. I felt the need to replace it with the right oil so that I knew it was done correctly.

After I was completed, I took the car out and test drove it for about 30 minutes. There was no moan when turning, the rear end was quiet when doing figure eights. I took it out on the main road, got it up to about 70 mph, then took it back, did some more figure eights and I have no complaint now. If you remember, I brought it back from the shop and I could still hear moans and clunks in the diff. I don't know if it's my own satisfaction or knowledge that the correct oil is in the diff but it runs as an 11k mile car should, it's quiet. I'm still not finished with the shop, I'm trying to hold them to a 30k warranty on my diff, they said they would need to talk to corporate but I'm not having high hopes that they will get back to me anytime soon. I'll keep pressing them at least to have it noted.

I want to thank everyone for their suggestions on the forum, I always lurk here but it's nice to know that I have a complete knowledge base at my fingers when I need one.

Thank you.

[Chutzpah]

Originally Posted by Sobak

Hey guys, I wanted to update all of you. The shop called me back and basically told me what I thought all along, they put the wrong gear oil in the system. They blamed it on their software recommending the wrong oil, I find that hard to believe. This morning I put the car on the lift and drained the diff again, what came out was consistent in color and smell to Dexron 88862624. I felt the need to replace it with the right oil so that I knew it was done correctly.

After I was completed, I took the car out and test drove it for about 30 minutes. There was no moan when turning, the rear end was quiet when doing figure eights. I took it out on the main road, got it up to about 70 mph, then took it back, did some more figure eights and I have no complaint now. If you remember, I brought it back from the shop and I could still hear moans and clunks in the diff. I don't know if it's my own satisfaction or knowledge that the correct oil is in the diff but it runs as an 11k mile car should, it's quiet. I'm still not finished with the shop, I'm trying to hold them to a 30k warranty on my diff, they said they would need to talk to corporate but I'm not having high hopes that they will get back to me anytime soon. I'll keep pressing them at least to have it noted.

I want to thank everyone for their suggestions on the forum, I always lurk here but it's nice to know that I have a complete knowledge base at my fingers when I need one.

Thank you.

Well, I’m glad it seems to have worked out for you. If they drag their feet, I’d ask them- Do I need to get a lawyer involved?…the car has 11K miles on it. The threat of a lawyer, may make them more receptive to giving you what you want. I just don’t think it’s much to ask… including your $ back, as well as paying YOU for you time effort and materials to change again. But that’s me…everyone has their own tolerance level for confrontation. Good luck.

[Coded4SS]

i once had a shop put in ATF in my manual cobalt SS trans which required gear oil basically. Dude said "red came out red went in". Certified and all that junk.

[UnknownJinX]

Originally Posted by Sobak

Hey guys, I wanted to update all of you. The shop called me back and basically told me what I thought all along, they put the wrong gear oil in the system. They blamed it on their software recommending the wrong oil, I find that hard to believe. This morning I put the car on the lift and drained the diff again, what came out was consistent in color and smell to Dexron 88862624. I felt the need to replace it with the right oil so that I knew it was done correctly.

After I was completed, I took the car out and test drove it for about 30 minutes. There was no moan when turning, the rear end was quiet when doing figure eights. I took it out on the main road, got it up to about 70 mph, then took it back, did some more figure eights and I have no complaint now. If you remember, I brought it back from the shop and I could still hear moans and clunks in the diff. I don't know if it's my own satisfaction or knowledge that the correct oil is in the diff but it runs as an 11k mile car should, it's quiet. I'm still not finished with the shop, I'm trying to hold them to a 30k warranty on my diff, they said they would need to talk to corporate but I'm not having high hopes that they will get back to me anytime soon. I'll keep pressing them at least to have it noted.

I want to thank everyone for their suggestions on the forum, I always lurk here but it's nice to know that I have a complete knowledge base at my fingers when I need one.

Thank you.

In my experience, their excuse is not as silly as you'd think. That happens sometimes.

Or again, they punched in the wrong car or wrong part.

[Sobak]

Originally Posted by UnknownJinX

In my experience, their excuse is not as silly as you'd think. That happens sometimes.

Or again, they punched in the wrong car or wrong part.

Normally I'd understand but when I picked up the car the second time, they told me they had to "Prime the cooler line" if they just would have been honest the first time, I might have been able to overlook the wrong fluid.

Anyway, everything seems to be running well now, no cold moan when turning on the last test drive.

[WhiteMale]

Some manual tranny's take ATF, that's not uncommon contrary to the logic of it.

[arpad_m]

Originally Posted by WhiteMale

Some manual tranny's take ATF, that's not uncommon contrary to the logic of it.

He got ATF poured into the rear differential.

OP, it looks like your car got away with minimal or no damage, yay. Hope you'll be able to wring the extra warranty out of the dealership.

[ctrlz]

If the diff is not making noise anymore, I suspect it is OK.

The ATF and gear oil are probably interchangeable over the short term. The oil portion of these fluids is designed to lubricate the rotating parts (i.e. gears) and dissipate heat.

The crucial difference here is the friction modifier package. This is what allows "locked" plates to slip. The needs in a limited slip diff vs. an automatic tranny are different. An LSD has springs continually applying pressure to the clutch surfaces. In a straight line they are always locked. On turning, we want the plates to slip instead of the tires slipping on the road. The friction modifier (well, a small bit of the total amount) sits between the plates and allows them to temporarily slide. Static friction turns to sliding friction. The friction modifier also helps dissipate the resulting heat to the rest of the gear oil.

In an ATF during shifts, clutch packs transition from 0% force to 100% force. It is during the transition that we want a friction modifier to smooth engagement. In this scenario the modifier should allow slippage for a bit and then not slip at all. We don't want any slip once it's 100% engaged.

The friction modifiers in ATF are basically "more grabby," which is why the OP's car made horrendous noise while turning.

From what I can find, the Dexron 75W-90 LS Gear Oil is a blended synthetic gear oil with this friction modifier added:
https://standards.globalspec.com/std/9966549/9985412
I would need to know exactly which ATF was used on the OP's diff to compare the additives directly.

[L78toLT1]

For what it’s worth, the recommended lubricant for the diff is the same shade of red as ATF. Also, despite the 75W 90 viscosity rating, it behaves differently than conventional trans/diff dope. It pours/drains about the same as motor oil. Don’t pull your drain plug and expect this stuff to drain out like molasses.

[Spaceme1117]

Originally Posted by L78toLT1

For what it’s worth, the recommended lubricant for the diff is the same shade of red as ATF. Also, despite the 75W 90 viscosity rating, it behaves differently than conventional trans/diff dope. It pours/drains about the same as motor oil. Don’t pull your drain plug and expect this stuff to drain out like molasses.

The GM fluid is a light yellow for the rear differential, not red.

I changed the diff fluid in my 2017 Camaro and my 2011 Corvette about a month ago. They use the exact same part number GM diff fluid and it definitely is not red.

[L78toLT1]

Originally Posted by Spaceme1117

The GM fluid is a light yellow for the rear differential, not red.

I changed the diff fluid in my 2017 Camaro and my 2011 Corvette about a month ago. They use the exact same part number GM diff fluid and it definitely is not red.

Well, damn! I suppose I must be thinking about the m6 fluid, which is red, as it should be since it actually is atf. My wife accuses me of getting senile, and she must be right. I track my car often and have changed the diff fluid a minimum of 5 - 6 times. My faulty memory apparently "remembered" the yellow/brown fluid as being red lol! What I am positive about though is that it isn't nearly as thick as you would expect.

[snekk]

I'd recommend a used oil analysis from Blackstone on your rear diff fluid to see if anything is wearing faster than it should for your mileage.