I have spoken to two corvette technicians about changing my transmission fluid (3 years is up) and one corvette tech said that I had to change my internal filter at the same time as the transmission fluid. The other tech asked me if I wanted to change the internal filter. I told both of them NO. In both cases, I didn't have time to debate the subject. Did GM change their Owner's Manual or did they put out a Tech bulletin about the internal transmission filter needing to be changed at 3 years. I have 18K miles on my car and you would think the internal transmission filter would not need to be replaced at 18K miles. If the internal filter is like the external filter, it should be based on mileage not three years. Maybe someone on the forum knows the mileage the internal filter needs to be changed at. Any thoughts appreciated.

 

The internal pan sump filter is supposedly a "lifetime" filter, so take that for whatever it's worth to you. There is no time or mileage requirement associated with it. With that said, I have seen some dealerships offering the service. I personally took advantage of it to get the cleanest/most fresh fluid in there as possible at the 3-year mark since it was only an additional $200 to have the service added. I'm by no means suggesting everyone do it, GM does not call for it, but I did take the opportunity to do so.

I had my original external canister filter changed at 6,900 miles and was in at the dealership around 21,500 miles, so I was due for the external canister filter at the same time as my 3-year fluid service. I'm personally a fan of fresh filter(s) to go with fresh fluid, but... Others opinions will vary

I also change and/or refresh my "lifetime" ATF fluids in other vehicles. Personal choice, but to me lifetime is another way of saying powertrain warranty period.

 

Agree - the internal is suppose to be lifetime - however, to error on side of caution I will have mine changed every other canister change.... can't over service these cars.

 

The problem with a lot of these inconsistencies is that the C8 and it’s DCT are not what service advisors and mechanics are used to. Your typical automatic has needed it’s internal filter changed regularly along with a real flush, not the flush called out in the external filter change.

 

Make sure you request percussive maintenance as well.

 

Like others said, there is not stated requirement to change the internal filter. And, in the version of the Service Manual that I have, there is drain and fill procedure that does not require the internal filter to be replaced. Now....to add..... many of the diagnostic procedures for transmission related DTCs start with simple remedies - like a level check - and then progressively more involved steps - like an hydraulic system flush and external filter replacement - and then even a simple drain and fill. If none of that stops the DTC from coming back, one of the last steps is to remove the pan, clean the pan and magnets, and replace the internal filter, then try again. After that, its time to replace a valve body or the transmission. From this one might conclude that someone at GM must think there are cases where the internal filter can require replacement. Further, the Maserati MC2, which uses the same TRMEC 8 speed transaxle, requires replacement of the internal filter every 8 years of 74560 miles. So, I can see an argument for replacing it. I had my three year fluid change, at 6000 miles, and did not have it replaced. The three years is more about the additive in the fluid beaking down, and not issues with debris. But I could see an argument for changing the internal filter based on mileage (like the external canister filter) but longer mileage intervals.

 

The internal filter housed within the transmission pan is a lifetime filter and does not need to be replaced. Anyone who elects to have it replaced out of an abundance of caution is not only wasting money they no idea what has to be done to get to that filter! If they knew they would absolutely never have it changed.

 

I know...and I had mine changed. It's not that much extra work with the car already on the lift and under panels removed (for as much as I dislike Rick Conti, he did a decent video on it). For all the DCT issues experienced in these cars, and with my car being modified more than most, I'm willing to spend the extra $200 out of an abundance of caution. I've also run the 2L track fill since PDI, and promptly did that again myself after getting the car back from the dealership 3-year service visit.

 

As mentioned, if you are having transmission problems, changing the internal filter is one part of the diagnostic procedure. If your transmission is not giving you problems, I see no need to change the internal filter. If GM comes out and says if you don't change your internal filter every so many miles, your warranty will be voided, then I will definitely change the filter.

 

Clearly we are not talking about the same filter. In order to replace the non serviceable DCT filter you have to remove the DCT oil pan which is not easy to access. They not only have to remove the rear sway bar they also must remove the transmission mounting bolts then they need to jack up the rear of the transmission in order to remove the DCT oil pan. There is no way I want anyone jacking up my transmission while it’s still attached to the engine talk about asking for trouble! Even after replacing the gasket it’s prone to leak. It’s very labor intense and no dealer is going to put that labor into it for $200.00.

AND PAY CLOSE ATTENTION TO THIER COMMENTS ABOUT HOW CLEAN THE OLD FILTER IS WITH NO DISTINGUISHABLE DIFFERENCES BETWEEN THE OLD AND NEW FILTERS.

The madness beginning @ 9mins 30seconds into the video.

You Tube

 

We're talking about the same filter; there's only two. The filter is roughly $60 wholesale + about an hour of labor. The filter isn't "non-servicable" as it is a scheduled maintenance item on other vehicles utilizing the same/similar transmission. The pan has a channel gasket and isn't prone to leaking more than any other AT pan of similar design. Many transmission pan & differential cover gaskets are now considered reusable due to the design, construction, & materials used. Same with the LT1/2 intake manifold and throttle body gaskets.

 

Again, not telling or even recommending anyone do it unless they want to. It's a service my dealership offers and I took them up on it. I clearly admit I "over maintain" and modify my vehicles so the extra precaution is warranted in my mind as I typically keep the ones I like beyond their warranty periods. Same reason I've refreshed the "lifetime" ATF & differential fluid in one of my Jeeps that I use as a tow rig. My wife's '23 Jeep was already on its 3rd round of differential & transfer case fluids @ ~21k miles, but we use that vehicle for intended purposes, as well.

 

Let’s speak truth here. It’s NOT a scheduled maintenance item for the C8 Corvette the rest of your comments are simply trying to justify doing it. It’s your money so do what you want but for the significant reasons I stated in my previous post owners should avoid changing it like the plague.

BTW, I still highly doubt the dealer did all that work for only $200 given the fact many of us paid far more just to have the serviceable DCT filter replaced.

 

I'm stating WHY I did it, simple as that. My reasoning differs from yours which is fine. I clearly noted that it's not required by GM. I waste $200 on far stupider things so I could careless about trying to justify it to anyone (especially as I know guys with cars sitting in the dealership waiting on parts, entire transmissions, etc). This work was performed less than 2 months ago (June 2024)... My total bill with tax was $1,190.37 which also included an alignment, annual state safety/emissions inspections, and R&R of the Borla exhaust system (which was covered under warranty with reimbursement for that line item from Borla). I also had a 20% off coupon from the dealer which helped knock down the total bill. Prior to the 20% off, the transmission service was $899 + tax for ACDelco ATF DCTF FFL-4 and both DCT filters ($699 + tax if you only want the required external filter replaced). The paperwork includes all associated part numbers for the fluid and filters, which I have verified to be accurate.

 

^^ You did say you car is modified. That may be a good reason to go for more maintenance than less. The more typical C8 owner doesn't do the same things you do. So, for them it may not be needed.

 

Indeed, sir! Fully agreed. I may not have the backing of a full GM powertrain warranty if my engine/transmission were to decide to kill itself 😉

My service advisor hasn't said anything yet about them (nor did he on my C7), but I'm also not naive if a problem were to occur.

 

Thinking you got unicorn pricing. They certainly did not quote me the same...

 

I’m OCD when it comes to maintenance and for sure I would change any existing filter on the car, required or not (especially since for other brands using the same/similar transmission, this is a required service item). However, some of the comments indicated the extreme surgery that we expose our car to, in order to change that inside filter and I’m totally against any extra work that’s performed by dealerships (my lack of trust is a different story). So, I’m now torn between wanting to change the filter but not wanting to dismantle my car just to do that. Any more comments that would help me decide one way or another?

 

That is NOT what I mean when I say that I'm going to take my car out and knock the carbon out of the engine. :-)

 

As expensive as these transmission are, I'd be all over changing these filters with each fluid change.