[Sobak]

So, I need some advice from this forum. I own a 2018 Camaro 2SS with only 11k miles on it. I wanted to get the rear differential fluid replaced due to the issues from the factory. I take it to a mechanic on 12/4 and he made the comment that the "rear differential takes ATF," It didn't register with me at the time, I figured they are an ASE Certified shop, they should know more than me....right?

Yesterday I wanted to go for a drive, I got a few miles from the house and my differential started making a god-awful sound, I drive it back home but before I pull in the garage I do some circles and I could hear the gears just wining in the back. I drive it home and park it.

Today I called the shop, they had it towed back and I pick it up today. The explanation to me was "We had to prime the cooler for the rear differential, that is what was making the noise" I hate to call BS......but BS, the cooler and the differential oil are closed systems, they shouldn't mix (From my understanding).

If it was a cooler problem, then why did I hear the gears when I made a turn? I've taken possession of the car a second time, I test drove it, the differential doesn't sound as bad as yesterday, but I still hear noise, it doesn't sound like I'd expect a differential on an 11k car to sound like. It clunks, moans and I hear things I don't think I should.

So my questions are...

1. Would an ASE Certified shop actually think that putting ATF in the rear differential is okay (I have the invoice to prove that they billed me for ATF)?

2. If that's the case, I drove the car 139 miles, what damage has happened?

3. I'm probably going to put my car on the lift this weekend and drain the differential again, if ATF comes out, what should I do if that is the case?

It's getting to the point where I'm thinking I can't find any reputable shop to work on my cars other than the dealer. I know you get what you pay for but I'm not shy when it comes to working on cars, I have my own portable lift, I've done my own oil changes and last weekend replaced the brakes on my wife Mazda CX-9. I treat my cars as they should be, with regular maintenance and moderate repairs, I take my cars to get fluids replaced because I just don't have the resources to dispose of the old fluids.

I appreciate your guys' insight into this, I'm kicking myself for not spending an hour or two doing the job myself.

[arpad_m]

As per the owner's manual, the recommended rear axle fluid for your car is Dexron 75W-90 LS gear oil with the limited slip friction modifier, which is a far cry from the recommended automatic transmission fluid for the same car.

I don't know how much damage 139 normal miles on the wrong fluid can cause to the differential, but you should flush it out and fill it with the proper juice ASAP.

(Even though I'm a relative noob, my approach to getting work done on the car is "trust, but verify 2x", for this very reason. Hopefully your car didn't suffer much or any damage.)

[Sobak]

Thanks arpad_m, I have visited this place a few times, it was recommended to me but now the trust is damaged. If they caught their mistake, they probably drained the differential today and filled it with the proper fluid but the damage has been done. If it wasn't for the noise I wouldn't have questioned it.

I think from now on, I'm going to take the time to change my own fluid. At least I know it was done right and I have no one to blame but myself.

[Chutzpah]

Wowza… good luck, hope it works out for you. I’d drain and fill it (twice). Then head to a parking lot, do 4 or 5 tight figure 8’s. Go for a 20 minute ride, drain and flush again. Repeat the figure 8’s.

If it makes you feel any better, I just had a TPMS sensor changed on my truck. The price included: balancing, new TPMS sensor and reprogramming.
Well, TPMS light came back on and I also heard a clicking sound from my wheel, at low speed. Looked at the tire and it had positional chalk marks from the tire to the wheel. So, now I look at the wheel and the weights are still the originals… and the tire has a small gouge in it. I bring the truck back and I ask if the wheel was balanced and if I can see the old TPMS sensor. Guess what? He admits the sensor is still in the wheel and “the tire doesn’t need to be balanced if it comes off exactly the way it was put on” ….and the light will go out in 50 miles or so. Oh, ok… thanks for clearing that up for me. Anyway, I told the guy what I thought of him and his mad skills, dared him to fight the cancellation of payment, then went across the street and had Humpty Dumpty put back together again. Unfortunately, this type of crap happens to all of us at one point or another (and this dude was recommended to me too)…

[Sobak]

Chutzpah, thanks, I just might do that, I would have more respect if he didn't try to BS me about having to prime the cooler, I'm giving him one last chance to come clean and tell me what was done. I will say that when trust is broken, I will never go back. I had one guy at an oil chang facility argue with me that oil evaporated and because I was two months out from changing it (date not miles) the oil evaporated.

I'm going to take your suggestion and do just that. I've already purchased my 15 qt oil change container, just hope my local Auto Zone as room to take my used oil. Thanks for comments.

[2SS Capt]

Originally Posted by Sobak

Chutzpah, thanks, I just might do that, I would have more respect if he didn't try to BS me about having to prime the cooler, I'm giving him one last chance to come clean and tell me what was done. I will say that when trust is broken, I will never go back. I had one guy at an oil chang facility argue with me that oil evaporated and because I was two months out from changing it (date not miles) the oil evaporated.

I'm going to take your suggestion and do just that. I've already purchased my 15 qt oil change container, just hope my local Auto Zone as room to take my used oil. Thanks for comments.

I'd take it back and show him the receipt (that shows ATF was used) and tell him your lawyer will be contacting him to send him the bill for the new rear differential...

I gotta think putting ATF into something designed for 75W-90 is going to trash it in short order, ATF is like water, 75W-90 is damn near like honey... (but smells like ass...)

Sucks that it happened and sorry you are dealing with this, but whenever possible, change your own fluids, especially in these high performance cars, the risk isn't worth it...

[UnknownJinX]

Maybe the dude looked at the transmission fluid specs somehow? Even then, V8 M6 and A10 use different types of ATF (Dexron III for M6, Dexron VI for A10).

Either way, that's a very amateur mistake and I would be very curious where they saw that info.

I am with arpad that you should really check the fluid specs for any fluids. Coolants especially can be a lot of fun.

Originally Posted by 2SS Capt

I gotta think putting ATF into something designed for 75W-90 is going to trash it in short order, ATF is like water, 75W-90 is damn near like honey... (but smells like ass...)

Sucks that it happened and sorry you are dealing with this, but whenever possible, change your own fluids, especially in these high performance cars, the risk isn't worth it...

I don't know if the viscosity that's gonna do OP's differential in here, especially for a street-driven vehicle. I think it's the additive package (or should I say the lack of correct additives) that's wreaking havoc on the clutches inside the LSD, hence the noise.

And yeah 75W-90 diff fluid is pretty thick when cold, though gear oil viscosity index is actually different from the engine oil viscosity index. Took me forever to pour some into the manual trans on my winter car Mazda3 yesterday. 75W-90 gear oil is similar to 5W-30 engine oil in viscosity IIRC.

[2SS Capt]

Originally Posted by UnknownJinX

Maybe the dude looked at the transmission fluid specs somehow? Even then, V8 M6 and A10 use different types of ATF (Dexron III for M6, Dexron VI for A10).

Either way, that's a very amateur mistake and I would be very curious where they saw that info.

I am with arpad that you should really check the fluid specs for any fluids. Coolants especially can be a lot of fun.



I don't know if the viscosity that's gonna do OP's differential in here, especially for a street-driven vehicle. I think it's the additive package (or should I say the lack of correct additives) that's wreaking havoc on the clutches inside the LSD, hence the noise.

And yeah 75W-90 diff fluid is pretty thick when cold, though gear oil viscosity index is actually different from the engine oil viscosity index. Took me forever to pour some into the manual trans on my winter car Mazda3 yesterday. 75W-90 gear oil is similar to 5W-30 engine oil in viscosity IIRC.

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...

[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

[2SS Capt]

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

That requires some "common sense", which unfortunately, isn't so "common" any more...

Honestly, this should be a VERY good lesson for ANYONE who has the LEAST BIT of ability to change their our own fluids (NO offense to the OP)... JUST DO IT YOURSELF... DO NOT LET ANY MINIMUM WAGE MORON TOUCH YOUR CAR... The outcome could be VERY EXPENSIVE!!! I would have never bought my car if I couldn't do 98% of the maintenance on it, I simply do not trust the commercial "drive in" maintenance places... (I wouldn't let them touch my Home Depot $200 push lawn mower, let alone my nearly $50,000 2020 2SS...)

[WhiteMale]

Remember though that the peeps doing fluid changes are the lowest ranking people in the shop and not some certified master mechanics. In excusable but you have to keep that in mind as no master mech is doing fluid changes.

[Sobak]

Thanks, guys, I appreciate all the comments. I'm still pissed at this the more I think about it. Here's the kicker that I left out of my original post. When they called me back the second time, I asked what the deal was, and he said, "we forgot to prime the cooler lines, sorry about that" That made my BS sensor go off the scale. There should have been no reason to even touch the cooler. Since the cooler dumps into the transmission, I should have had problems with my transmission as well. Plus, simply having the cooler lines not working wouldn't cause the gears to make noise.

I'm through messing with the shops, while convenient all it takes is one screwup and the car is toast. The last shop I went to told me that my oil was low due to evaporation. I've ordered my 16-quart container and will be working this weekend changing out the fluid just to make sure it's done properly.

[Spaceme1117]

Well that sucks. Hopefully, your differential is not damaged but it very likely is. And if so, they owe you for a new diff and all of the labor involved.

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.

You could maybe go back to shop that did the "work", speak to the manager or owner , tell them the situation and see what they will do for you. Then I would have the car towed to a Chevy dealership, tell them what has been done, and ask them to drain the fluid and document everything. And see what they say about damage to the differential and what should be done. And if there is damage, present the estimate to the shop and proceed from there.

And if you can, change fluids yourself.

[dmcmahan60]

Hold the shop and the mechanic 100% liable for the mistake. The receipt should show what fluid was used and have the correct fluid put in it. If your rear diff takes a dump it is on them. Sometimes you have to be an A$$ to make them understand you are not happy and will not accept it until the mistake is fixed. Good luck. An ASE certified mechanic should have known better. No excuse for that. An when I say be an A$$ I mean just talk to the manager and voice your concerns.