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I was at the Shanghai auto show a couple of weeks ago. Place was packed in the wings where manufacturers were displaying new cars. So I was wandering aimlessly as I often do about the upper floors where the parts suppliers had their displays set up. I happened to come across the Finest company that specialized in transmissions. I was admiring what looked to be a traditional 9 speed automatic that was sliced open so you could view the internals.
Interestingly enough it had an electric motor integrated into the transmission so a manufacturer could make a standard rear wheel drive car into a hybrid without affecting traditional packaging. As I was admiring the transmission a well dressed gentleman with a German accent started chatting to me about the features of this transmission. Turns out he was the lead transmission engineer and had been involved in the design of this and other transmissions. We chatted about transmissions for a few minutes and the subject of Tremec and the C8 transmission came up. I mentioned some of the issues GM had been having with the C8 DCT transmission. He says I have just the DCT solution for you, get an Audi with a DCT. I said you find the Audi a good DCT transmission? He said yes it is very reliable and durable, and, I was the lead engineer on the Audi DCT project. So we chatted a bit more and at one point asked him how often do you recommend changing the DCT fluid in the Audi DCT? He gave me a look and said never. The Audi DCT fluid is as he put it "fluid for life". Really?????? Meanwhile the Tremec fluid goes rotten just sitting in the bottle let alone being used in the transmission.
Hmmm (conspiracy theorists of the world unite as ominous music plays in the background) Maybe this is GM and Tremecs new "Transmission service as a subscription" Many dealers are making big bucks off the required transmission service every 3 years times ultimately 300,000 plus cars. At a $1,000/per car every 3 years works out to $100,000,000 per year in C8 transmission service.
In all seriousness I do wonder if Audi can design a DCT that never needs DCT fluid replacement then why couldn't GM and Tremec do the same thing? (or at least not deteriorate just sitting in the bottle on a shelf somewhere)
Ford only requires the DCT fluid (Titan FFL-4 - same as the C8) in the Tremec TR9070 DCT to be changed every 40K miles with no time limit. The 3 year requirement is something GM/Tremec came up with specifically for the TR9080 DCT transaxle.
Last edited by RKCRLR; May 15, 2025 at 10:47 AM.
Reason: Corrected C8 fluid requirement
My 2008 BMW Z4 owner’s manual says 100,000 automatic transmission fluid/filter change. I asked the dealer and they said follow the manufacturer’s recommendation. Of course when the transmission fails, they get a hefty repair charge, and are happy to take your money.
Ford only requires the DCT fluid (Titan FFL-4 - same as the C8) in the Tremec TR9070 DCT to be changed every 40K miles with no time limit. The 3 year and 7,500/15,000/22,500 mile requirement is something GM/Tremec came up with specifically for the TR9080 DCT transaxle.
Actually the Vette fluid is only changed every 45k mi. The filter changed early at tighter intervals due to clutch residue clogging the valves on some cars. Too bad Ford couldn't build a car competitive to Corvette for $100k, but it took $500k to do it and only a few got to own one. I know loads of C8 owners and not one has had trans problems. Audi the purveyor of high quality? Most all German brands have lower quality numbers than American cars.
Actually the Vette fluid is only changed every 45k mi. The filter changed early at tighter intervals due to clutch residue clogging the valves on some cars. Too bad Ford couldn't build a car competitive to Corvette for $100k, but it took $500k to do it and only a few got to own one. I know loads of C8 owners and not one has had trans problems. Audi the purveyor of high quality? Most all German brands have lower quality numbers than American cars.
Oops, you're right, I confused the filter and fluid requirements but there is still a 3 year requirement for the fluid. I'll correct my post.
I was at the Shanghai auto show a couple of weeks ago. Place was packed in the wings where manufacturers were displaying new cars. So I was wandering aimlessly as I often do about the upper floors where the parts suppliers had their displays set up. I happened to come across the Finest company that specialized in transmissions. I was admiring what looked to be a traditional 9 speed automatic that was sliced open so you could view the internals.
Interestingly enough it had an electric motor integrated into the transmission so a manufacturer could make a standard rear wheel drive car into a hybrid without affecting traditional packaging. As I was admiring the transmission a well dressed gentleman with a German accent started chatting to me about the features of this transmission. Turns out he was the lead transmission engineer and had been involved in the design of this and other transmissions. We chatted about transmissions for a few minutes and the subject of Tremec and the C8 transmission came up. I mentioned some of the issues GM had been having with the C8 DCT transmission. He says I have just the DCT solution for you, get an Audi with a DCT. I said you find the Audi a good DCT transmission? He said yes it is very reliable and durable, and, I was the lead engineer on the Audi DCT project. So we chatted a bit more and at one point asked him how often do you recommend changing the DCT fluid in the Audi DCT? He gave me a look and said never. The Audi DCT fluid is as he put it "fluid for life". Really?????? Meanwhile the Tremec fluid goes rotten just sitting in the bottle let alone being used in the transmission.
Hmmm (conspiracy theorists of the world unite as ominous music plays in the background) Maybe this is GM and Tremecs new "Transmission service as a subscription" Many dealers are making big bucks off the required transmission service every 3 years times ultimately 300,000 plus cars. At a $1,000/per car every 3 years works out to $100,000,000 per year in C8 transmission service.
In all seriousness I do wonder if Audi can design a DCT that never needs DCT fluid replacement then why couldn't GM and Tremec do the same thing? (or at least not deteriorate just sitting in the bottle on a shelf somewhere)
Any thoughts?
This info is true for Audi and BMW. For BMW, the autos require a trans fluid service at the end of break-in, after that no recommended fluid changes.
the transmission you were looking at is the “mild” hybrid system where the electric motor is integrated with the transmission.
I happen to agree with your theory. In my mind it’s a way for GM to recoup cost of development and warranty claims on a novel DCT.
I don't think there is any conspiracy going on to keep the dealers busy or deny warranty claims. However, I do suspect the 3 year requirement is overly conservative.
Probably some GM engineer(s) didn't like something about the properties of the fluid, no controlled specification, the fluids ability to absorb moisture, additive breakdown, etc. so an overly conservative requirement was put in place.
Perhaps something used in the TR9080 is more sensitive to additive breakdown or moisture, perhaps edge cases. I.e., old fluid foaming during track use, too much moisture when a rarely driven car lives in a humid environment, etc.
It would be nice if we had access to know what the concern is so we could make our own decisions once the car is out of warranty.
Actually the Vette fluid is only changed every 45k mi. The filter changed early at tighter intervals due to clutch residue clogging the valves on some cars. Too bad Ford couldn't build a car competitive to Corvette for $100k, but it took $500k to do it and only a few got to own one. I know loads of C8 owners and not one has had trans problems. Audi the purveyor of high quality? Most all German brands have lower quality numbers than American cars.
OR EVERY 3 YEARS for the fluid. The DCT filtr is milage only (7500, 22500, every 22500 after that) track use excepted (every 24 track hours.
The shelf life and functional life (the three years in the car) are different requirements. "Shelf life is the period following the lubricant’s manufacture during which it is deemed suitable for use without re-testing its physical characteristics. Functional life is determined by durability or accelerated life testing of a lubricant in a component under expected operating conditions. " A lubricant might last much longer in its container - but the manufacturer has just not tested its properties for longer than that. The functional life, in the case of the C8, according to Josh Holder, is because the additive package deteriorates after the fluid has been put in the car.
You can put the fluid in the car at or near the end of its "shelf life" and it is still good for three years in the car (or 45000 miles etc).
I do not believe that the three year shelf life has anything to do with GM specific influence. It goes back to the original Fuchs Titan product - so it appears to be a Fuchs specified shelf life.
On functional life:
From a Josh Holder statement: ".... "The fluid needs to be changed after 3 years because the anti-foaming agents will break down and the fluid will absorb some moisture. All service recommendations are for good reason ."
Last edited by Andybump; May 15, 2025 at 12:57 PM.
My Porsche 911’s PDK transmission (which is Porsche speak for a DCT) requires fluid changes every 120,000 miles or 12 years. So yeah, a 3 Year fluid life is strange.
Actually the Vette fluid is only changed every 45k mi. The filter changed early at tighter intervals due to clutch residue clogging the valves on some cars. Too bad Ford couldn't build a car competitive to Corvette for $100k, but it took $500k to do it and only a few got to own one. I know loads of C8 owners and not one has had trans problems. .
Read the footnotes. OR every 3 years, whichever comes first.
As for the German guy recommending a German product with a DCT that he apparently designed, that's sort of like a politician saying "trust me."
My Porsche 911’s PDK transmission (which is Porsche speak for a DCT) requires fluid changes every 120,000 miles or 12 years. So yeah, a 3 Year fluid life is strange.
The Porsche doesn't use the same fluid for the clutches as for the rest of the gearbox. I suspect that's why it lasts for so long. The clutches are the major wear items. Does the PDK also include the differential (is it a transaxle) or only a transmission. I think it's only a tranny, so the loads from the final drive gears don't affect the fluid.
...He said ... I was the lead engineer on the Audi DCT project....how often do you recommend changing the DCT fluid in the Audi DCT? He gave me a look and said never. The Audi DCT fluid is as he put it "fluid for life". Really?????? ...
Hmmmm: According to Audi:
However I have also read that the DSG fluid should be replaced at 4 years.
I was at the Shanghai auto show a couple of weeks ago. Place was packed in the wings where manufacturers were displaying new cars. So I was wandering aimlessly as I often do about the upper floors where the parts suppliers had their displays set up. I happened to come across the Finest company that specialized in transmissions. I was admiring what looked to be a traditional 9 speed automatic that was sliced open so you could view the internals.
Interestingly enough it had an electric motor integrated into the transmission so a manufacturer could make a standard rear wheel drive car into a hybrid without affecting traditional packaging. As I was admiring the transmission a well dressed gentleman with a German accent started chatting to me about the features of this transmission. Turns out he was the lead transmission engineer and had been involved in the design of this and other transmissions. We chatted about transmissions for a few minutes and the subject of Tremec and the C8 transmission came up. I mentioned some of the issues GM had been having with the C8 DCT transmission. He says I have just the DCT solution for you, get an Audi with a DCT. I said you find the Audi a good DCT transmission? He said yes it is very reliable and durable, and, I was the lead engineer on the Audi DCT project. So we chatted a bit more and at one point asked him how often do you recommend changing the DCT fluid in the Audi DCT? He gave me a look and said never. The Audi DCT fluid is as he put it "fluid for life". Really?????? Meanwhile the Tremec fluid goes rotten just sitting in the bottle let alone being used in the transmission.
Hmmm (conspiracy theorists of the world unite as ominous music plays in the background) Maybe this is GM and Tremecs new "Transmission service as a subscription" Many dealers are making big bucks off the required transmission service every 3 years times ultimately 300,000 plus cars. At a $1,000/per car every 3 years works out to $100,000,000 per year in C8 transmission service.
In all seriousness I do wonder if Audi can design a DCT that never needs DCT fluid replacement then why couldn't GM and Tremec do the same thing? (or at least not deteriorate just sitting in the bottle on a shelf somewhere)
Any thoughts?
I believe it is because of the transaxle part. Since the axles and rear diff use the same fluid the intervals are more frequent is my understanding after talking to the trans engineers at the Bash.
Unfortunately your german person is wrong. My kid has a 2025 A4 with the DCT transmission and it requires a service (fluid and filter change ) every 40K miles.
My Porsche 911’s PDK transmission (which is Porsche speak for a DCT) requires fluid changes every 120,000 miles or 12 years. So yeah, a 3 Year fluid life is strange.
Same with my 911. The Porsche maintenance guide only refers to PDK "clutch oil" and PDK "transmission oil" to be changed at 12 years or 120K miles. There is no mention of differential oil in their maintenance guide.
I was at the Shanghai auto show a couple of weeks ago. Place was packed in the wings where manufacturers were displaying new cars. So I was wandering aimlessly as I often do about the upper floors where the parts suppliers had their displays set up. I happened to come across the Finest company that specialized in transmissions. I was admiring what looked to be a traditional 9 speed automatic that was sliced open so you could view the internals.
Interestingly enough it had an electric motor integrated into the transmission so a manufacturer could make a standard rear wheel drive car into a hybrid without affecting traditional packaging. As I was admiring the transmission a well dressed gentleman with a German accent started chatting to me about the features of this transmission. Turns out he was the lead transmission engineer and had been involved in the design of this and other transmissions. We chatted about transmissions for a few minutes and the subject of Tremec and the C8 transmission came up. I mentioned some of the issues GM had been having with the C8 DCT transmission. He says I have just the DCT solution for you, get an Audi with a DCT. I said you find the Audi a good DCT transmission? He said yes it is very reliable and durable, and, I was the lead engineer on the Audi DCT project. So we chatted a bit more and at one point asked him how often do you recommend changing the DCT fluid in the Audi DCT? He gave me a look and said never. The Audi DCT fluid is as he put it "fluid for life". Really?????? Meanwhile the Tremec fluid goes rotten just sitting in the bottle let alone being used in the transmission.
Hmmm (conspiracy theorists of the world unite as ominous music plays in the background) Maybe this is GM and Tremecs new "Transmission service as a subscription" Many dealers are making big bucks off the required transmission service every 3 years times ultimately 300,000 plus cars. At a $1,000/per car every 3 years works out to $100,000,000 per year in C8 transmission service.
In all seriousness I do wonder if Audi can design a DCT that never needs DCT fluid replacement then why couldn't GM and Tremec do the same thing? (or at least not deteriorate just sitting in the bottle on a shelf somewhere)
Any thoughts?
But it's much less frequent and not as expensive (taking into account Audi labor rates)
Time will tell, but it seems that the Valvoline full synthetic FFL-4 DCT fluid is not only better, but a fraction of the cost of the overpriced GM fluid while still meeting the spec required.
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Magic DCT fluid?
