Transmission Service
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Instructor
Joined: Oct 2022
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Transmission Service
I stopped at the dealer today and talked to them about a transmission flush and filter and price. After arguing with the service writer for 10 minutes she finally got the service manager. He told me that there are 2 different transmissions in the C8 a standard one (nonZ51) and a heavy-duty one (Z51). He also told me that the standard one couldn't be flushed only the heavy duty one and that now GM says the transmission needs a fluid and filter change every 7500 miles. I told him I thought he was wrong about not being able to flush the standard unit (had never heard there were 2 variations) and he should look into it. Can anyone verify any of this?
Safety Car
Joined: Jul 2019
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From: Florida
I stopped at the dealer today and talked to them about a transmission flush and filter and price. After arguing with the service writer for 10 minutes she finally got the service manager. He told me that there are 2 different transmissions in the C8 a standard one (nonZ51) and a heavy-duty one (Z51). He also told me that the standard one couldn't be flushed only the heavy duty one and that now GM says the transmission needs a fluid and filter change every 7500 miles. I told him I thought he was wrong about not being able to flush the standard unit (had never heard there were 2 variations) and he should look into it. Can anyone verify any of this?
The DCT filter change procedure which includes the valve flush (not to be confused with a transmission fluid flush) is available in the dealership servicing procedure. Id direct them to that.
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Instructor
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The DCT filter change intervals are in the owner's manual. I'd direct your dealership to it.
The DCT filter change procedure which includes the valve flush (not to be confused with a transmission fluid flush) is available in the dealership servicing procedure. Id direct them to that.
The DCT filter change procedure which includes the valve flush (not to be confused with a transmission fluid flush) is available in the dealership servicing procedure. Id direct them to that.
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Instructor
Joined: Oct 2022
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lol, I hear that! It's hard to trust anyone these days about anything, at least that's been my experience lately. Thinking about just doing it myself except I wouldn't be able to perform the flush. Assuming there is one for a non Z51 which my gut tells me there is and the service manager doesn't know ****.
Safety Car
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From: Florida
With the problems that are starting to appear on the transmission along with the fact that there is an updated transmission now it wouldn't surprise me if the service intervals of the transmission might have changed and is not in a 3 year old owners manual. It wouldn't be the first time. But I will definitely have them look at the service procedures again. Thanks!
The owner's manuals are available online. ...they are immediately updatable and you can look at all years as well.
What doesn't surprise me is that your dealership is providing completely false information.
That's why I always suggest that you ask them to reference the actual documents.
You'll find that they quickly either go silent or start to change their story.
Pro
Joined: Jul 2021
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From: Crosslake, MN
I stopped at the dealer today and talked to them about a transmission flush and filter and price. After arguing with the service writer for 10 minutes she finally got the service manager. He told me that there are 2 different transmissions in the C8 a standard one (nonZ51) and a heavy-duty one (Z51). He also told me that the standard one couldn't be flushed only the heavy duty one and that now GM says the transmission needs a fluid and filter change every 7500 miles. I told him I thought he was wrong about not being able to flush the standard unit (had never heard there were 2 variations) and he should look into it. Can anyone verify any of this?
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Thread Starter
Instructor
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Thanks for your input. I knew the Z51 and nonZ51 had different differentials but didn't realize that the trans and differential was one unit. Maybe the mechanical limited slip unit doesn't have an electronic flush feature. More investigation will clear things up.
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From: Florida
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https://www.tremec.com/anexos/Litera...R-9080.DCT.pdf
https://www.tremec.com/anexos/SAE_In...ansmission.pdf