jackpilot

I've searched the entire internet!

I can't seem to find one write-up on a DIY transmission fluid change for the Corvette C7 A8 automatic transmission.

Anyone have a link?

Most appreciated!

Internets_Ninja

Thats because its not as simple as just draining the fluid and refilling. To do it properly you need a machine that can pull the old fluid out and push the new fluid in.

Dcasole

You cant possibly have that many miles on you car yet can u …….Why are u worrying about it ?

Dave

dash7510

Good luck. I was curious a while back and couldn't find any valuable information.

sevinn

I just bought a c7 and it's shuddering so I'll be doing this soon. I don't want to wait the 3 weeks all the local dealers are telling me for trans diagnostics. I tuned it out for now but I'll be diy-ing within the next month or so.

jackpilot

Yeah, my dealer had the car for 2 weeks to complete the triple flush due to lift availability for Corvettes at the dealership. It fixed 98% of the vibration issues. I can still see the RPM jumping like before, but without the associated shuddering.

I purchased the Range AFM delete module and plugged it in so I don't have to worry about the V4/V8 crap shaking my car apart.

But I would like to know how to change the fluid on my own due to tracking the car and I'm crazy about changing all my fluids at least twice a year. I may also try to install the LG Stage 2 transmission cooling kit and would like to have some sort of DIY tutorial.

Avanti

If it's like other new vehicles, there isn't even a way for the customer to check the fluid level, much less change it. Days of doing such are rapidly disappearing.

Dcasole

makes perfect sense ...... I looked all over the internet also and did not find anything , I wonder if it's like the C6 , drop the pan , change filter then fill using the sight plug on the side

Dave

jackpilot

That's kinda what I'm thinking but wanted to get some advise from someone who has already done it.

Flame Red

^ Agree

I believe there is a forum vendor that sells a nice aluminum tranny pan that has cooling fins, extra capacity, and a drain. I could not find it again to point it out. It was pricey as I recall. But was nicer looking than when I welded a drain on the c6 pan!

I did not buy it because I suspect I'll be having GM eventually working the A8 again for me. They replaced the A8 with only 100 miles on the clock already and it is starting some weird noises with 7K. I don't want to give GM any excuse to deny a warranty/ extended warranty claim which I expect is coming.

JHEBERT

Internets_Ninja

lol you guys need to read the service manual on how to change/flush automatic transmission fluid in the A8. Then you will understand how it is not a weekend warrior job. The days of dropping the pan and swapping fluid is long gone. You certainly are not going to fix a shudder issue without having the proper GM equipment to do it.

The HACK

BINGO. Most of the modern automatic transmission fluids require a mechanical pump to replace. You need to hook it up to a transmission cooler line, pump fluid in to push the old fluid out. I believe the car has to be running to so the torque converter pump is active as well, since the majority of the fluid is stored in the converter.

Not a "shady tree" mechanic job for sure. For that, you need a manual transmission.

jackpilot

Bollocks! Thanks guys.

JocLean

Hi Jackpilot. I own a C7 'Vette with the 8 speed transmission. I changed the ATF pan fluid and the filter yesterday. Completed in my garage using front tire ramps and two jackstands supporting the rear end. The car was level for all procedures. Safety always comes first, so I made sure to use top quality ramps and jackstands, employed properly. Full disclosure: I am not a professional mechanic...just a weekend warrior who has owned corvettes since 1979. I call this type of work my hobby. If you don't know what you are doing or can't work with safety, take your car to a service station.

You can read procedures on this forum for the A6 transmission fluid/filter change. Check out those posts, as the A8 is similar.

Now for the A8 8L90 details as I experienced them. Esentially you are going to drain the fluid (as best you can); pull the pan; pull the filter; clean the pan and magnets; push in a new filter; clean the pan mating surfaces and gasket; replace the pan and gasket and torque the pan bolts to spec. All the typical stuff. Remember, safety first and proper torque in a crossing pattern.

Now the ugly details: GM did not make this easy.
The fill tube is behind an exhaust pipe. I used an 80 degree needle-nose pliers to unlock the fill tube plug and remove the fill tube plug. Insert a length of 3/4 inch O.D. (or less) vinyl tube into the ATF fill tube to drain most of the ATF from the pan. (I fashioned a metal support to guide the vinyl tube.)

The rear four pan bolts are difficult to reach. I removed the four 15 mm nuts from the transmission / differential supporting cross member. Then I carefully and gently raised the transmission about one inch to gain access to the four rear ATF pan bolts. (Be careful not to damage the ATF pan) Lower the transmission once the four rear pan bolts are removed. Remove the pan; remove the old filter; clean everything; replace the filter; replace the pan and pan bolts. Lift the transmission about one inch to torque the rear pan bolts to 89 inch lbs. Torque pan bolts in the required crossing pattern. Lower the transmission. Replace the transmission support crossmember nuts and torque to 35 foot lbs.

For a pan fluid and filter change, the 8L90 transmission requires 7.4 quarts of the latest Dexron HP fluid (Mobil 1 Synthetic ATF LV HP with the Blue Label). Place a vinyl fill tube in the ATF fill tube and put the 7.4 quarts into the transmission pan. Replace the ATF fill tube plug.

Follow the available protocols to check for leaks and to determine that the proper level of ATF is in your transmission. This entire maintenance procedure is not a difficult job, and if you have basic mechanic skills you should be able to complete this maintenance in less than 2 hours. I have not stated all the details (like gasket protections), but you experienced weekend warriors will know what to do...safely.

JocLean

Tinkertech

There is a write up on how to do it in the 'sticky' forum. Don't need any really special tools. Don't even need to drop the pan. just suck it out and pump in new. Run engine to mix. Repeat until you have gone thru 24 Qts. I have done mine this way twice, once with the black label Mobil1 fluid and then again with the blue label fluid. ~3 to 4 hours if your 'slow and old' like me.

JocLean

The above weekend warrior instructions are for those individuals who want to change (not flush) the Corvette Stingray 8L90 A8 ATF pan fluid and change the ATF filter, as required in the GM owner's maintenance requirements for severe service (required in the 2016 owners manual). If you want to keep your 8L90 A8 transmission in good shape you will regularly (about every 40,000 miles) change the ATF pan fluid and the ATF filter. This allows you to see and clean what is in the bottom of the ATF pan and what is on the ATF magnets. (Flushes will change all the fluid, but the ATF filter is not changed and the pan is not cleaned in an ATF "flush.") I can tell you that the filter material in the ATF filter I replaced, looked....well, I'm happy I replaced it.

Regarding the online CF sticky notes (and other online site notes) on Corvette Stingray 8L90 A8 transmission fluid and filter changes -- they are somewhat applicable to the Corvette A8, but they are mistaken or delinquent in a few major aspects. They do not cover the replacement of the ATF filter. There is no easy-to-use drain plug on the Corvette A8. The ATF drain and fill tube is difficult to utilize. There is nothing on how to access the rear ATF pan bolts. There is nothing regarding the 7.4 quarts required to refill the Corvette 8L90 ATF pan. Information regarding the latest correct Dexron HP fluid (July 2019: Mobil 1 Synthetic ATF LV HP with the Blue Label) is scarce. For example, my local GM dealer Corvette service manager confirmed that the latest Dexron HP fluid is backward compatible with the factory Dexron HP ATF. I posted the above to communicate some real world information to C7 Corvette owners. For those of you who have the requisite mechanical and safety skills, you can save money and know that the job is done right: Safety, fluids, filters, quantities, torque, fluid levels, etc., all to specifications on your favorite GT.

lakemg

Thanks JocLean for the info. Does the latest and greatest ATF fluid have a new part number? If I go to all the trouble of changing it, I want to make sure that I get the latest and greatest.

JocLean

Lakemg:
The latest and greatest part numbers for the C7 8L90 transmission fluid and filter change (July 2019) are:
Fluid GM Part No. 19417577. This part was delivered to me in the Mobil 1 Synthetic ATF LV HP (Blue Label) bottles, by the local dealership. You will need 8 quarts, as you will refill the pan with 7.4 quarts of fluid. (That level of fluid refill resulted in about one ounce of fluid draining from the drain-check tube during the ATF level check, at about 95 degrees Fahrenheit ATF temperature.)
Filter GM Part No. 24274402. There is no gasket required with this part, as the gasket is an integral part of the filter.

The most difficult part of this process is dealing with the refilling of the ATF pan. You can do it!

JocLean

BlueDevilZ51

Here's a great detailed video on a fluid change on the 8L90 (A8).