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I took my '17 GS (17k miles, I've owned it since last Nov) into the shop to change some fluids (oil and differential) along with an alignment prior to an upcoming trip to Tail of the Dragon. My service advisor (who has always treated me well) called and said, "We need to talk about the diff."
He told me there were "lots" of shavings on the magnetic plug and the fluid was clearly full of metal particles. He's uneasy about me making the trip with the current differential. Of course, the fluid was already disposed of and I couldn't see it for myself.
I haven't had one hint that there was an issue. No noise at any speed. No vibration. Nothing. Is this common for a failing differential?
I don't think I've read anything about C7s having issues with their differentials, but maybe I've missed it?
I'm looking for insight, best guesses, a magic chant, whatever. Thanks in advance.
I assume that you posted this message because of the insensible contradictions about the condition of your C7 diff. For example, the service adviser who works on commission explained:
-lots of shavings on the mag plug
-fluid full of metal particles
And here is the contradiction:
-The car has not given you a hint of a problem
-You hear no noise at any speed
-No vibration
-The C7 diff has an excellent durability history record
-And it is disturbing that the shop did not save any evidence of the metal particles.
I serviced the diff in my C7 at 30K miles, and the plug did have a bit of metallic mud. Many forum members have reported that the old diff fluid does have a bit of a metallic silver appearance. Mine did. If it was my car, I would have the shop refill the diff with new fluid. Ensure that it is 75W-90. Enjoy your trip. In the future, consider a different shop.
Given some personal experience with bogus reports for big-item "repairs" by dealerships, and given all you've said, I'd suggest putting in new lube, driving a short while, draining, and seeing for yourself what comes out. If it was really that bad there will still be identifiable shaving in the oil at that point. If not, I'd find somewhere else to go back to next time. All the best.
Given some personal experience with bogus reports for big-item "repairs" by dealerships, and given all you've said, I'd suggest putting in new lube, driving a short while, draining, and seeing for yourself what comes out. If it was really that bad there will still be identifiable shaving in the oil at that point. If not, I'd find somewhere else to go back to next time. All the best.
Bingo. These diffs always generate metal shavings in the process of breaking-in. I just did a first replacement of my 2019 Z06 diff fluid at 24k miles and 5 years and I did find some debris on the drain plug magnet and some on the fill plug which also has an identical magnet. If the differential sounds good to you, I am sure it is as such and no need for you to worry just because a service advisor is trying to sell you a repair job by scaring you. I have always waited until 20k miles or more before doing a diff fluid change and never have had a problem before or after with such diffs on a number of previous vettes. My son and I had an 08 coupe and 06 Z06 that had the well-known low speed turning chatter that was resolved to changing to AMSOIL Severe Gear with extra additive. GM fixed it going forward with the factory fill DEXRON LS fluid starting with MY2009.
If they disposed of the fluid, ok I guess - depending on their disposal/drain system. But to not save or at the least provide pics of the "shavings" for you to see is inexcusable these days. In other words, just trust us we don't need to prove our findings to you - you probably wouldn't understand.
But to not save or at the least provide pics of the "shavings" for you to see is inexcusable these days. In other words, just trust us we don't need to prove our findings to you - you probably wouldn't understand.
Agreed, sure is a lot of money not to snap one pic of the evidence described. As recommended- change fluid, check after a couple drives. If burnt, dirty looking, or metallic particles then- okay. If not, let her rip.
If they disposed of the fluid, ok I guess - depending on their disposal/drain system. But to not save or at the least provide pics of the "shavings" for you to see is inexcusable these days. In other words, just trust us we don't need to prove our findings to you - you probably wouldn't understand.
Curious what is the service advisor recommending?
That was strange as well. He didn't push for the work, just "hey, I don't know if I'd take the trip if it were my car." So, not a hard sell. But, I've been very easy to work with up to this point.
I will say that I asked him for a quote so I knew what I was looking at and I still haven't seen it 24 hours later.
Hello @DD17GS
In will be of great value to forum members if you would post to this thread the outcome of the issue with your diff. Thanks
I'm planning on driving it as much as possible for the next couple of weeks and checking the fluid. I'll check back in with an update and a planned course of action.
I'm planning on driving it as much as possible for the next couple of weeks and checking the fluid. I'll check back in with an update and a planned course of action.
Thank you, everyone, for your comments.
To my recollection, everyone who has DIY changed out the factory fill diff fluid has reported that it looked gunky with metallic debris in evidence. I think this is just the nature of a new diff wearing-in normally over a span of thousands of miles. The typical issues that might arise with a daily driver differential may be that there is a wear pattern that developed because speeds were not varied over the first few hundred miles breaking-in resulting in whining noise. The other might be shaft seals leaking. Failure of the diff gearing and bearings, a big no.
Differential Advice
Bingo. These diffs always generate metal shavings in the process of breaking-in. I just did a first replacement of my 2019 Z06 diff fluid at 24k miles and 5 years and I did find some debris on the drain plug magnet and some on the fill plug which also has an identical magnet. If the differential sounds good to you, I am sure it is as such and no need for you to worry just because a service advisor is trying to sell you a repair job by scaring you. I have always waited until 20k miles or more before doing a diff fluid change and never have had a problem before or after with such diffs on a number of previous vettes. My son and I had an 08 coupe and 06 Z06 that had the well-known low speed turning chatter that was resolved to changing to AMSOIL Severe Gear with extra additive. GM fixed it going forward with the factory fill DEXRON LS fluid starting with MY2009.
