DCT filter change or not?
Racer
Joined: Jun 2020
Posts: 470
Likes: 276
If DCT Fluid Life % less than 10%, change fluid and filter & reset DCT fluid life %
If last DCT Fluid change 3 years ago, change fluid & reset DCT fluid life %
Odometer = 7,500 miles, change DCT filter
Odometer = 22,500 miles, change DCT filter
Odometer = 45,000 miles, change DCT filter & Fluid
Odometer = 67,500 miles, change DCT filter
Odometer = 90,000 miles, change DCT filter & fluid
If last DCT Fluid change 3 years ago, change fluid & reset DCT fluid life %
Odometer = 7,500 miles, change DCT filter
Odometer = 22,500 miles, change DCT filter
Odometer = 45,000 miles, change DCT filter & Fluid
Odometer = 67,500 miles, change DCT filter
Odometer = 90,000 miles, change DCT filter & fluid
E-Ray, 3LZ, ZER, LIFT
Joined: Sep 2007
Posts: 35,067
Likes: 12,429
From: NE South Carolina
First Service, DCT filter, Rick Corvette Conti, YouTube, starting at 5:50, Published 6/2/21, no mention of flush or leak test.
Call 10 dealers and the answer will be: yes, no, i don't know, never heard of this, etc.
https://www.youtube.com/watch?v=mtAy77x2NMQ&t=1s
Call 10 dealers and the answer will be: yes, no, i don't know, never heard of this, etc.
https://www.youtube.com/watch?v=mtAy77x2NMQ&t=1s
Good video.Some surprising things:
- The filter cover plate comes with 4 new bolts. They aren't small #10 bolts that could perhaps be torque to yield! So why new when they are only torqued to 53 in-lbs = 4.4 ft-lbs? Perhaps they include a special preinstalled sealent so they don't leak? You can see a brown material on the threads about 1/2 inch up from the bottom.
- Chuck's eyebrows raised when he said he had to reposition his lift pads "several times" to get access to the fill location. From prior video's Chuck does NOT used GM 2 1/2 inch diameter lift pads in the oval slots (which IMO is safer for the average tech to be sure the the car is being lifted where GM states on the frame.) So their lift pads would be raising the GM pads. Chuck is obviously capable and understanding where the locations are safe. Don't know if I would trust the average tech.
- They used a pressurized whatever to get the fluid into the check/fill hole. Doesn't look like a lot of room.
- Chuck also said you had to run the car and put in all gears for about 45 seconds mostly to get fluid to fill the dual clutch section. He said you have to check the level no more than 5 minutes after or fluid will drain from the clutch area and you'll have a false level reading. In that case it would be high. Similar to the C7 dry sump where if you waited longer than 10 minutes with the engine off, excess oil would drain back to the pan and you'd get a low reading in the tank!
- Chuck showed it used roughly a half quart of fluid. That's 16 oz much more than most have reported as required. Also subjectively looked and more than came out. Perhaps Rick's trans was low on fluid?
Last edited by JerryU; Jun 17, 2021 at 01:08 PM.
Race Director
Joined: Aug 2016
Posts: 12,866
Likes: 10,274
From: Garden Valley CA
- The filter cover plate comes with 4 new bolts. They aren't small #10 bolts that could perhaps be torque to yield! So why new when they are only torqued to 53 in-lbs = 4.4 ft-lbs? Perhaps they include a special preinstalled sealent so they don't leak? You can see a brown material on the threads about 1/2 inch up from the bottom.
He also didn't chase the threads (or didn't show it) which is called out in the procedure to remove the old thread locker and contamination. There is a caution note associated with that step to make sure the screws get properly torqued.
Last edited by RKCRLR; Jun 17, 2021 at 01:23 PM.
E-Ray, 3LZ, ZER, LIFT
Joined: Sep 2007
Posts: 35,067
Likes: 12,429
From: NE South Carolina
I believe GM called that a Top Off to replace fluid that's trapped inside filter.
One thing to think about: How many miles does GM and Mfg. of the DCT think it takes to wear in Clutches & Gears? it appears to be 7,500 miles.
Lets say you only have 1,500 miles on Trans, You have the Trans Filter replaced at 1,500 miles, That's 6,000 miles before GM & Mfg. consider internals are wore-in.
Question is, if at 1,500 miles the Gears and Clutches, etc. are not worn-in, and you don't do next Trans Filter Change until XX,XXX miles later, is your decision to do so putting the Trans at a greater risk of failure later on?
I say, change your oil at 1,500 mile or 1 year, if you want the 'Free One", then again at 7,500 miles, along with DCT filter replacement and top off, OUT OF POCKET, that is if C8 has 7,500 miles on it.
That would be bad, if it was not for Synthetic Oils we use now, as they don't absorb moisture like Dino oil Did.
That at least puts you on GM's recommend mileage change intervals for DCT Fluid & Filter s, along with less chance of Trans parts not being wore in per GM, an debris trapped in the filter, for XX,XXX miles before next change.
I'm sure you can afford to do that. It also allows proper time for Trans parts to wear in per GM & Trans Mfg. .
Based on your current 1,500 miles 1st year of ownership, It may take you up to 5 yrs before Trans Fluid & Filter needs to be changed per GM.
One thing to think about: How many miles does GM and Mfg. of the DCT think it takes to wear in Clutches & Gears? it appears to be 7,500 miles.
Lets say you only have 1,500 miles on Trans, You have the Trans Filter replaced at 1,500 miles, That's 6,000 miles before GM & Mfg. consider internals are wore-in.
Question is, if at 1,500 miles the Gears and Clutches, etc. are not worn-in, and you don't do next Trans Filter Change until XX,XXX miles later, is your decision to do so putting the Trans at a greater risk of failure later on?
I say, change your oil at 1,500 mile or 1 year, if you want the 'Free One", then again at 7,500 miles, along with DCT filter replacement and top off, OUT OF POCKET, that is if C8 has 7,500 miles on it.
That would be bad, if it was not for Synthetic Oils we use now, as they don't absorb moisture like Dino oil Did.
That at least puts you on GM's recommend mileage change intervals for DCT Fluid & Filter s, along with less chance of Trans parts not being wore in per GM, an debris trapped in the filter, for XX,XXX miles before next change.
I'm sure you can afford to do that. It also allows proper time for Trans parts to wear in per GM & Trans Mfg. .
Based on your current 1,500 miles 1st year of ownership, It may take you up to 5 yrs before Trans Fluid & Filter needs to be changed per GM.
Couple of things make me think most (initial higher) wear occurred in that first ~1000 miles.
First: Gears typically have matted and worn high spots in 500 to max 1000 miles. Companies making performance differentials mostly say 500 miles and some 1000 before using the car for towing.
Second: Another (higher initial) wear area is the multidisc clutches. Could feel my 1st gear clutch slipping when coming to a slow stop for about 1000 miles. Now at 3000 it is hardly noticeable. Stopped pulling both paddles when coming to a stop after the 1st month.
So IMO No Way does it take 7500 miles. GM probably used 7500 because it matches the time engine oil must be changed- 12 months or roughly 7500 miles. Clutch disks, just like in a "slushbox automatic" continue to have some small wear but in a typical "automatic" can last >100,000 miles.
The Owner's Manual footnote 4 says change DCT fluid after max 3 years. So like engine oil there is a maximum time which requires a fluid change. I have no concern changing at ~4000 miles (free) and next year will have ~8000 miles. Could change the filter again (and if I thought it was a warranty issue would) BUT think I will wait for the next filter change at 3 years when I'll have ~12000 miles and do it with a fluid change.
Last edited by JerryU; Jun 17, 2021 at 01:37 PM.
Race Director
Joined: Aug 2016
Posts: 12,866
Likes: 10,274
From: Garden Valley CA
I believe GM called that a Top Off to replace fluid that's trapped inside filter.
One thing to think about: How many miles does GM and Mfg. of the DCT think it takes to wear in Clutches & Gears? it appears to be 7,500 miles.
Lets say you only have 1,500 miles on Trans, You have the Trans Filter replaced at 1,500 miles, That's 6,000 miles before GM & Mfg. consider internals are wore-in.
Question is, if at 1,500 miles the Gears and Clutches, etc. are not worn-in, and you don't do next Trans Filter Change until XX,XXX miles later, is your decision to do so putting the Trans at a greater risk of failure later on?
I say, change your oil at 1,500 mile or 1 year, if you want the 'Free One", then again at 7,500 miles, along with DCT filter replacement and top off, OUT OF POCKET, that is if C8 has 7,500 miles on it.
That would be bad, if it was not for Synthetic Oils we use now, as they don't absorb moisture like Dino oil Did.
That at least puts you on GM's recommend mileage change intervals for DCT Fluid & Filter s, along with less chance of Trans parts not being wore in per GM, an debris trapped in the filter, for XX,XXX miles before next change.
I'm sure you can afford to do that. It also allows proper time for Trans parts to wear in per GM & Trans Mfg. .
Based on your current 1,500 miles 1st year of ownership, It may take you up to 5 yrs before Trans Fluid & Filter needs to be changed per GM.
One thing to think about: How many miles does GM and Mfg. of the DCT think it takes to wear in Clutches & Gears? it appears to be 7,500 miles.
Lets say you only have 1,500 miles on Trans, You have the Trans Filter replaced at 1,500 miles, That's 6,000 miles before GM & Mfg. consider internals are wore-in.
Question is, if at 1,500 miles the Gears and Clutches, etc. are not worn-in, and you don't do next Trans Filter Change until XX,XXX miles later, is your decision to do so putting the Trans at a greater risk of failure later on?
I say, change your oil at 1,500 mile or 1 year, if you want the 'Free One", then again at 7,500 miles, along with DCT filter replacement and top off, OUT OF POCKET, that is if C8 has 7,500 miles on it.
That would be bad, if it was not for Synthetic Oils we use now, as they don't absorb moisture like Dino oil Did.
That at least puts you on GM's recommend mileage change intervals for DCT Fluid & Filter s, along with less chance of Trans parts not being wore in per GM, an debris trapped in the filter, for XX,XXX miles before next change.
I'm sure you can afford to do that. It also allows proper time for Trans parts to wear in per GM & Trans Mfg. .
Based on your current 1,500 miles 1st year of ownership, It may take you up to 5 yrs before Trans Fluid & Filter needs to be changed per GM.
I asked the question about when the DCT is considered broken-in in another thread but didn't get an answer. However, the main reason for the break-in period is the DCT and GM doesn't consider the car fully broken-in for track use until 1500 miles so I'm going to go with that.
I asked the Corvette Concierge a similar question related to warranty and this is what I got:
I asked:
My understanding is the 7500 mile DCT filter change is included in the free service if performed within the first year of ownership.
Given the current environment I will probably put significantly fewer than 7500 miles within the first year.
What is the minimum mileage that I can have the 7500 mile DCT filter service performed and still retain the powertrain warranty?
The CC answered:
Thank you for reaching back out to the Corvette Concierge and great question! Prematurely servicing the DCT transmission in your Corvette will not void your powertrain warranty. With that said, we would encourage you to inquire with your assisting Chevrolet dealership for additional information pertaining to if this service will be complimentary as this offer may vary from dealer to dealer.
Le Mans Master
Joined: Apr 2020
Posts: 6,380
Likes: 3,294
As promised in my post #36, I went to my dealership's class A technician and he confirmed to me and then rechecked his computer with the procedures and it said that it is only a filter change and top off of apx 6oz of fluid via the plug.
He also mentioned (after looking at the notes on his screen) that there is NO fluid change required until 45,000 miles. The first year/7,500 and 22,500 are ONLY filter changes.
The first scheduled fluid change is at 45,000 Miles. Most cars have Tx fluid change service at 3/30K or 3/36K. I guess that with all of the filter changes, the first Tx fluid change is not necessary until then.
BTW, the schedule for all of this and more is in your OM starting on page 287 (2020 MY). P291 has the chart. Tx fluid change is mentioned only by the % in footnote 5. Again, my technician said that will be at or before 45K.
He also mentioned (after looking at the notes on his screen) that there is NO fluid change required until 45,000 miles. The first year/7,500 and 22,500 are ONLY filter changes.
The first scheduled fluid change is at 45,000 Miles. Most cars have Tx fluid change service at 3/30K or 3/36K. I guess that with all of the filter changes, the first Tx fluid change is not necessary until then.
BTW, the schedule for all of this and more is in your OM starting on page 287 (2020 MY). P291 has the chart. Tx fluid change is mentioned only by the % in footnote 5. Again, my technician said that will be at or before 45K.
Last edited by C8J; Jun 17, 2021 at 03:04 PM. Reason: Typo
Race Director
Joined: Aug 2016
Posts: 12,866
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From: Garden Valley CA
Did you get the document number he was looking at? Document ID 5384826 requires the hydraulic system flush prior to filter replacement. Was it a later document?
Last edited by RKCRLR; Jun 17, 2021 at 03:17 PM.
Racer
Joined: Jun 2020
Posts: 470
Likes: 276
the housing is aluminum and a post on another forum said the screws are also aluminum. The material on the new screws is thread locker. That is probably why they need to be replaced.
He also didn't chase the threads (or didn't show it) which is called out in the procedure to remove the old thread locker and contamination. There is a caution note associated with that step to make sure the screws get properly torqued.
He also didn't chase the threads (or didn't show it) which is called out in the procedure to remove the old thread locker and contamination. There is a caution note associated with that step to make sure the screws get properly torqued.
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Le Mans Master
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If I had to guess (not done naturally) I think some things (or footnotes) are being misinterpreted. The flush before the change (if you dig deeper) is for a Tx defect vs normal preventative care. I do not believe a flush is required for the 7500/1year Tx Filter change without an existing Tx defect. My GUT concurs until proven otherwise. Besides, it was performed by the dealer so my warranty is still in effect - if done incorrectly, but I do not think so.
Le Mans Master
Joined: Apr 2020
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Guessing from picture 2" diameter, 4" height = 12.5cuin = 6.6 floz
Last edited by C8J; Jun 17, 2021 at 05:13 PM.
Race Director
Joined: Aug 2016
Posts: 12,866
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From: Garden Valley CA
No I just observed him reading his screen with his information on what is required. I have never felt a need to double check behind him.
If I had to guess (not done naturally) I think some things (or footnotes) are being misinterpreted. The flush before the change (if you dig deeper) is for a Tx defect vs normal preventative care. I do not believe a flush is required for the 7500/1year Tx Filter change without an existing Tx defect. My GUT concurs until proven otherwise. Besides, it was performed by the dealer so my warranty is still in effect - if done incorrectly, but I do not think so.
If I had to guess (not done naturally) I think some things (or footnotes) are being misinterpreted. The flush before the change (if you dig deeper) is for a Tx defect vs normal preventative care. I do not believe a flush is required for the 7500/1year Tx Filter change without an existing Tx defect. My GUT concurs until proven otherwise. Besides, it was performed by the dealer so my warranty is still in effect - if done incorrectly, but I do not think so.
@robertbruce has posted in this thread that their tech did the flush procedure prior to changing the filter.
And @ChiTownVetteTech says he does the flush when he does a filter change.
It's possible that some shops aren't using the latest procedure.
Last edited by RKCRLR; Jun 17, 2021 at 05:11 PM.
Racer
Joined: Jun 2020
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. As I've said, I'm not worried as it was done by a certified C8 tech. I'm covered with the warranty regardless and everything is working just fine.
Le Mans Master
Joined: Jul 2013
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From: Morrill Nebraska
When you dig deeper it also says not to perform the flush unless directed by another procedure. In this case the DCT filter change procedure directs you to perform the flush procedure.
@robertbruce has posted in this thread that their tech did the flush procedure prior to changing the filter.
And @ChiTownVetteTech says he does the flush when he does a filter change.
It's possible that some shops aren't using the latest procedure.
@robertbruce has posted in this thread that their tech did the flush procedure prior to changing the filter.
And @ChiTownVetteTech says he does the flush when he does a filter change.
It's possible that some shops aren't using the latest procedure.
Racer
Joined: Jun 2020
Posts: 470
Likes: 276
When directed to the flush or leak test, it then reads:
Flush reads: This procedure is used to flush the transmission fluid through the filtration system before a repair is performed that may have been caused by debris in the fluid.
Leak Test reads: This procedure is used to test the transmission for leaks after a repair.
We are not repairing, we are changing the filter and/or a fluid drain and replace (these are called maintenance).
Flush reads: This procedure is used to flush the transmission fluid through the filtration system before a repair is performed that may have been caused by debris in the fluid.
Leak Test reads: This procedure is used to test the transmission for leaks after a repair.
We are not repairing, we are changing the filter and/or a fluid drain and replace (these are called maintenance).
Race Director
Joined: Aug 2016
Posts: 12,866
Likes: 10,274
From: Garden Valley CA
When directed to the flush or leak test, it then reads:
Flush reads: This procedure is used to flush the transmission fluid through the filtration system before a repair is performed that may have been caused by debris in the fluid.
Leak Test reads: This procedure is used to test the transmission for leaks after a repair.
We are not repairing, we are changing the filter and/or a fluid drain and replace (these are called maintenance).
Flush reads: This procedure is used to flush the transmission fluid through the filtration system before a repair is performed that may have been caused by debris in the fluid.
Leak Test reads: This procedure is used to test the transmission for leaks after a repair.
We are not repairing, we are changing the filter and/or a fluid drain and replace (these are called maintenance).
So, what DCT filter replacement maintenance procedure should be followed if not Document ID 5384826?
According to @ChiTownVetteTech the requirement to flush the hydraulic system was a recent addition within the last few months. It is quite possible that the flush procedure was initially written for repaired DCTs only. After GM learned some more about problems with the DCT (perhaps residual contamination left over from manufacturing or excessive contamination during break-in) they may have decided to invoke the flush procedure as part of filter change procedure without rewording the flush procedure.
Last edited by RKCRLR; Jun 17, 2021 at 08:32 PM.
Thread Starter
Race Director
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From: Central Illinois
Is changing the filter one step in checking when there is a problem and so because there is a code, you should change the filter to try and clear it, but before you do that you need to run the flush to try and also remove all particulate with the filter change? So is there routine filter change AND a filter change that needs flush to try and clear a debris problem?