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You may call GM, And you may get differing answers. You willvhave to decide if you are going with a call to a GM rep, or going with the latest recommendation in the documentation. Its not just about the warranty - it about what should be done to protect the transmission. The later requirements are being made for a reason (in my opinion).
One of the script answers the GM reps give is "do what your owners manual says". For 2023 your Owners Manual says change it at 7,500 miles. Did that mean "or sooner"? Based on later information, it did not.
As far back as late 2020 or early 2021, GM reps in public forums have been stating that "at" mean "at" not before. They provided examples verbally saying if change at 3000 miles, it must be changed again at 7,500 miles. It has to do with the fact that the break in period for the transmission is 7,500 miles (also not stated in 2020-2022 manuals) and during that time it is, ostensibly, still shedding debris that can fill the filter up. The statement about the 7,500 mile break-on for the transmission first appeared in your 2023 manual. But, the clarification regarding the tolerance around the "at 7,500 miles" did not appear until the 2024 manual. It did appear in the Service Manuals before that. I changed mine at 2,500 miles but I will change it again between 7000-8000 miles.
The first clip is from the 2023 manual. The next two are from a service manual and a 2024 Owners Manual.
One detail, the note does not say the break-in is complete at 7500 miles. It says the filter must be changed at 7500 miles during the break-in period without defining what the break-in period is. The interval between the 7500 mile filter change and the next DCT filter change (22,500 miles) is 15K miles while all other filter changes are at 22,500 mile intervals. This implies that the DCT is still being broken after the 7500 mile change and the same "tight" interval would apply then. I.e., if it is changed earlier than 22,500 one could argue it should be changed again at 22,500 miles using the same logic as the 7500 mile change requirement.
Personally, I think it is a ridiculous requirement. The original filter is good for up to 8K miles but if it is swapped out at 6999 miles the replacement filter is only good for 1000 miles. But if it is swapped out at 7000 miles (one mile later) then the same filter is good for another 15K miles.
One detail, the note does not say the break-in is complete at 7500 miles. It says the filter must be changed at 7500 miles during the break-in period without defining what the break-in period is. The interval between the 7500 mile filter change and the next DCT filter change (22,500 miles) is 15K miles while all other filter changes are at 22,500 mile intervals. This implies that the DCT is still being broken after the 7500 mile change and the same "tight" interval would apply then. I.e., if it is changed earlier than 22,500 one could argue it should be changed again at 22,500 miles using the same logic as the 7500 mile change requirement.
Personally, I think it is a ridiculous requirement. The original filter is good for up to 8K miles but if it is swapped out at 6999 miles the replacement filter is only good for 1000 miles. But if it is swapped out at 7000 miles (one mile later) then the same filter is good for another 15K miles.
I know. As written it can create some odd situations that don't make sense. But how easy is it to write a requirement that accounts for each different early change and then indicates the corresponding mileage for the subsequent changes? To frame the problem, if one changes the filter at 10 miles instead of 7,500 miles, then I think its clear the next change still needs to be at 7,510 miles or close to that. if one changes it a 7500 miles, then the next change is at 22,500 miles. So as the first change moves from 0 to 7500 miles, the second change moves from 7,500 miles to 22,500 miles. Its a non-linear progression - you just cant add a fixed number to the first change to find the mileage for the second change. If you change it at 3000 miles, can you just add 15000 miles and change it at 18000? And then is it ok to go another 22,500 miles.
The Maseratti MC20, using the same transmission, and presumably the same filter (though that is an assumption) calls for a change every 9320 miles. Forever. The period does not lengthen.
I know. As written it can create some odd situations that don't make sense. But how easy is it to write a requirement that accounts for each different early change and then indicates the corresponding mileage for the subsequent changes? To frame the problem, if one changes the filter at 10 miles instead of 7,500 miles, then I think its clear the next change still needs to be at 7,510 miles or close to that. if one changes it a 7500 miles, then the next change is at 22,500 miles. So as the first change moves from 0 to 7500 miles, the second change moves from 7,500 miles to 22,500 miles. Its a non-linear progression - you just cant add a fixed number to the first change to find the mileage for the second change. If you change it at 3000 miles, can you just add 15000 miles and change it at 18000? And then is it ok to go another 22,500 miles.
The Maseratti MC20, using the same transmission, and presumably the same filter (though that is an assumption) calls for a change every 9320 miles. Forever. The period does not lengthen.
Have an alternate method for determining when the filter needs to be changed (like a table or graph) if you didn't want to use the more consitave method. I'd prefer that to a requirement that doesn't make sense. I could figure it out...
When something doesn't make sense I don't believe it.
Have an alternate method for determining when the filter needs to be changed (like a table or graph) if you didn't want to use the more consitave method. I'd prefer that to a requirement that doesn't make sense. I could figure it out...
When something doesn't make sense I don't believe it.
Ok. Here is an example. It could also be table, i suppose. This is
mileage at the 2nd change = 2*mileage at first change+7,500 miles.
I think even this is pessimistic because it is a linear relationship. Although the endpoints are correct, in between I think the mileage of the second change would faster. Even this may not be safe though. If the second change is early, must the third change also be less that 22,500 miles from the second.
Ok. Here is an example. It could also be table, i suppose. This is
mileage at the 2nd change = 2*mileage at first change+7,500 miles.
I think even this is pessimistic because it is a linear relationship. Although the endpoints are correct, in between I think the mileage of the second change would faster. But this one is safe.
I agree, something like that as an alternate method would work for me. Unfortunately it does not comply with the current requirement and some would argue that it would void the warranty because of that.
Yep can argue with GM's statements and rules and what YOU think is logical! But as I say, GM's Warranty, GM Rules. Agree sounds silly to say if changed at say 6500 miles you have to change the filter (with FLUSH) 500 miles or max 1500 miles later.
BTW if you had 6999 that is NOT GM's silly requirement it's your foolishness! Even if ~6500 miles take a long drive before bringing it in!
SIDEBAR: (LONG SHAGGY DOG STORIES RE WHY CAN'T JUST IGNORE GM's RULE!)
Consider it has nothing to do what you think, the Tech at the dealer OR the dealership owner.
First a possible technical reason: When I had my filter 1st replaced, year one FREE on GM's dime, the super Tech (who just did my E-Ray PDI and will do my 1st year service at my "guess" <3000 miles where I will take advantage of GM's FREE service offer as I did my 2020 C8) showed me what GM stated in their Filter Service requirement on his PC re requiring a FLUSH prior. It said the flush will send any debris into the filter housing where it will be removed with fluid in the housing! So the filter is not clogged at say 1000 miles, but debris could be removed during the replacement process.
Before replacing a DCT the dealer MUST get approval from GM Service. Not the Tech's or Dealership choice!
GM is funny, and have been since the early 1960s from my experience. My Uncle was a Service Manger (before becoming GM) at a large Chevy Dealer. (Same Uncle that helped when I was 17, assembling an Olds engine from parts that I stuffed in my 1st car, a '41 coupe.) I was in his office when he had a truck head gasket in his hand putting a groove in a sealing passage. I asked what he was doing? He said GM requires us to keep all parts replaced on Warranty (~60 days as I recall) AND send any they request within that time to them. He said "We don't keep things like a removed head gasket but if they must have, I'll supply!"
Had a cracked clutch pressure plate on my 1st new car a 1967 Chevy, after 6 months. Looked like a casting defect to me (didn't need a microscope or our Met Lab to see an inclusion in the broken face) and my Uncle agreed. BUT he could not authorize replacement. Had to wait for their GM Service rep to visit with the car apart to show the flywheel face, clutch disk were perfect so it was not abuse. A clutch is considered a wear part and is not covered under warranty. Rep agreed it was a defect and got new one FREE.
Similar with the hole on my C6 Vette AC Condenser. Local Dealer Service manager said, "Just like a paint chip that was caused by a rock, not covered, as GM will say the hole was caused by a rock." After getting the failed condenser home, showed with pics it was a manufacturing defect. Local GM service rep agreed, and I got the full $800 I paid to have it replaced, refunded.
Yep can argue with GM's statements and rules and what YOU think is logical! But as I say, GM's Warranty, GM Rules. Agree sounds silly to say if changed at say 6500 miles you have to change the filter (with FLUSH) 500 miles or max 1500 miles later.
BTW if you had 6999 that is NOT GM's silly requirement it's your foolishness! Even if ~6500 miles take a long drive before bringing it in!
SIDEBAR: (LONG SHAGGY DOG STORIES RE WHY CAN'T JUST IGNORE GM's RULE!)
Consider it has nothing to do what you think, the Tech at the dealer OR the dealership owner. .....
These issues with warranty are a PITA but they aren't unique to GM. Last Nov we bought a 2024 Infiniti for my wife. After we had it for one week and 400 miles, we got the dreaded "Service CVT" warning message. The dealership's tech diagnosed it as a bad sensor the first day. Unfortunately he said that the sensor was built into the valve body and could not be replaced independently. Also, the didn't have a valve body in stock and had to find one...which is a different part than used in the 2022 and 2023. They needed to get approval for the work...but the Nissan/Infiniti corporate people made him spend a week on and off trying other things before they would believe him. Finally, they approved the work and we waited 4 1/2 more weeks for the part to arrive then he fixed it in one day once he had the part. Had the tech not had to go through corporate for approval and then wait for the part, it would have been fixed in two days instead of 5 1/2 weeks total. The dealership provided us with a free loaner for the entire time and their tech spent way, way, more time on it than he needed to. So this had to have cost the dealership a lot of money. Back in the 80's I had a similar experience with a Mustang GT I had...completely different part/problem but the same issue in that the dealership couldn't just go ahead and do what they knew they needed to.
Yep but must read the footnotes. This is Foot Note #4 and #5:
(4) Or every three years, whichever comes first.
(5) Check the transmission fluid life percentage. If the percentage is less than 10%, replace the fluid and filter. The initial transmission canister filter change must be performed at 12000km (7,500mi), and every 36000km (22,500mi) thereafter.
PS: Percent Fluid Life Useless in my 2020 C8. It does not consider time as does the OLM in C7 and C8. BTW my C6 OLM was also useless re time. It did NOT keep track of time, that was your job! The Owner's Manual (like my 1988 and 1993 Vettes where there was NO OLM) also said MUST be charged minimum every 12 months.
So just got off the phone with the dealership tech and he said since I only have 2200 miles on the car I do not need to do the transmission fluid change...I said 7500 is for the filter, the flush has to be done at 3 years (which is in the footnote)...he said he talked to his corvette specialist and said i dont need to do it.
How are these guys so inept that they cant get the simple service schedule right?
So just got off the phone with the dealership tech and he said since I only have 2200 miles on the car I do not need to do the transmission flush....I said 7500 is for the filter, the flush has to be done at 3 years (which is in the footnote)...he said he talked to his corvette specialist and said i dont need to do it.
How are these guys so inept that they cant get the simple service schedule right?
There is no requirement to do a transmission flush on the C8, if fact a transmission powerflush is specifically prohibited. There is a requirement to do a hydraulic system flush when the DCT filter is changed but it is an internal procedure and no fluid is replaced during a hydraulic system flush.
The 3 requirement is for the DCT fluid change, not a flush.
There is no requirement to do a transmission flush on the C8, if fact a transmission powerflush is specifically prohibited. There is a requirement to do a hydraulic system flush when the DCT filter is changed but it is an internal procedure and no fluid is replaced during a hydraulic system flush.
The 3 requirement is for the DCT fluid change, not a flush.
Here is the
"GM Offers Updated TechLink Article on Servicing the Transmission in the C8 Corvette"By Keith Cornett
You should read it all and pay attentin to the highlighted areas.
Pat
Last edited by Pat Salerno; 03-19-2024 at 01:45 PM.
Yep the key's are, quoting: The filter does not need to be changed earlier than 7,500 miles (12,000 km). Additional filter changes can be performed, but the recommended mileage intervals should still be followed for regular maintenance. For example, if a customer elects to have the filter changed before 7,500 miles (12,000 km), it should be changed again at 7,500 miles (12,000 km). GM will only cover one filter change.
The DCTF FFL-4 C8 Corvette transmission fluid should always be shaken vigorously prior to adding fluid to a vehicle in order to disperse the additives throughout the fluid. The fluid has a shelf life in the bottle of three years. (Fig. 6)
Funny, they now show the fluid life is on the container is max 3 years. The 1st version of this Tech Link actually quoted MY FORUM POST and suggested of the many expensive additives added to DCT fluids some are time life dependent. Like the extreme pressure additives they might be using in this relatively low viscosity fluid versus normal dif lubs. It was stated that could be something a dealer tech could tell a customer.
I had condensed and posted a very long Tech Article on Lubrication. They picked it up. NOW show even in the container it is shelf life dependent. Nope it's not like engine oil!
So for my 3 year service with 2200 miles I am asking for :
oil change
transmission fluid change ( do not change filter)
is that correct and how many quarts for trans fluid should they be using?
these guys don’t want to change the fluid
Yep, filter change not required but if records don't show it was never changed (as I did free year 1 with <3000 miles) then I would change the original filter. The required flush will get the initial wear debris flushed out and whatever is in the filter removed.
Mine took about 9.5 quarts. Once the aluminum aero panel is removed to access the drain plug, it's little labor to replace the filter. 4 screws remove the cover. Essentially the filter cost and the 8 oz of "dirty fluid" in the filter housing.
Yep, filter change not required but if records don't show it was never changed (as I did free year 1 with <3000 miles) then I would change the original filter. The required flush will get the initial wear debris flushed out and whatever is in the filter removed.
Mine took about 9.5 quarts. Once the aluminum aero panel is removed to access the drain plug, it's little labor to replace the filter. 4 screws remove the cover. Essentially the filter cost and the 8 oz of "dirty fluid" in the filter housing.
I gave my dealer 12 quarts for mine and never got any back... I hope they went to good use. Maybe the mechanic had his own C8 too? lol...
Where is this chart coming from? I'm not seeing it anywhere in the owner's manual for my 23. I see "296 Servjce and maintenance" at the top of the chart but in my manual, Service and aintenance starts on page 302 and there is no chart, just text with the intervals. I'm also not finding any reference to a "three year service". Is this something that changed for 23?
03-16-2024, 08:28 PM
