Gearhead Jim

Today I was speaking with the Corvette tech at our local dealer, he's a very sharp guy who owns a C6 and works on a lot of C7's because of his reputation.

He's been told recently by people in GM that they are coming out with yet another transmission fluid designed to fix the A8 shudder problem. According to what he was told:
The new fluid will be from Mobil, in bottles that looks similar to the one currently recommended, but with a different part number.
Initial deliveries of the fluid will be to dealers and areas that are having the most A8 problems, but he doesn't know who or where they are. Exact timetable is unknown.
The basic procedure will remain to do a drain and refill with the new stuff, if problem recurs then do another drain and refill. There may be more.
GM seems hopeful that this will be the "final solution" to the A8 shudder problem. Yes, we've heard that before.
He speculates that if a second drain/refill with the new stuff doesn't solve the problem, then GM may authorize a new TC or tranny, but that's just his personal guess.
The most recent bulletin about this is #16-NA-175, dated October 11 2018, before this "latest and greatest" fluid. That bulletin will updated with the new fluid and procedure.

It will be interesting to see how this fits with the recently filed class action lawsuit against GM regarding A8 problems, discussed in another thread here.

There is a old bulletin #16-NA-355 that is about remote start kits and has nothing to do with A8 problems.
When I find a copy of 18-NA-355, I'll post a link unless someone beats me to it.

Usually I refrain from posting unverified information, but this guy usually knows what he's talking about. Of course, his information is only as good as what he gets from GM.
He says he can't recall replacing any A8 converters or trannys on Corvettes because of the shudder problem, the fluid changes and/or updating to latest program seem to have worked for the cars he's handled. But that's a rather small sample in the big scheme of things, and I didn't ask about his experience with A8 problems on other GM products.

Personal experience: Our 2017 Z51 A8 has just over 20k miles, operated in Drive 95% of the time and lots of long trips with lots of V4 use. It has the typical "wavering" +/- 50rpm or more in V4, but I can't feel or hear it. This Fall I had him do a drain/refill with the then-newest fluid as a precaution. No problems before, no problems since.
But again, a sample of 1 doesn't prove anything.

04TRCorvette

Can we get them to change to the new transmission fluid under warranty even if we do not have any problems? I got my 2016 A8 last October and have no problems. Sometimes rough shift but nothing that's too bad. But was hoping to get the new stuff if its better. I have a range plugged in, i hated the V4 thing.

MMD

Gearhead Jim

Noted and corrected, thanks.

Gearhead Jim

A good question, especially since I've already paid once to get the then-newest fluid in hopes of preventing problems.
My guess is that the answer will be "No", unless GM does it as part of a settlement from the lawsuit.

555ctsv

Taking mine in next week to get it done before i install the 2300

Stew24

I've got this problem, but my OCD cringes at the thought of anyone tearing into my new car to make so called "repairs"! I'm in Arkansas and my '17 Grand Sport has displayed this issue prominently, since DAY#1! Coming from a C6 with a 6 speed manual, and never having test driven a C7 Grand Sport with an automatic 8 speed transmission before I purchased, I didn't know if this wasn't normal operation for this model??? It didn't take me too long to conclude for sure, this is a defect! I've had to explain what to expect when ever I've let my wife drive the car. I have actually developed personal "driving techniques" to lessen the impact of the hard shifting, pushing, snatching and hesitation acceleration characteristics! I want to be a part of any litigation or resolution to addressing this issue!

Tom/99

Interesting, thank you.

cstapp99

I know how you feel, but you should bite the bullet and take it in. The fluid swap did wonders for my car. I'm hoping the issues don't return, but if they do I'll take my car back in and ask for the newest fluid.

Idaho Mark

tcinla

some fluid will fix a design flaw? Miraculous!!!
.
You can call me a pessimist but, I tend to think the worst (I guess I am a pessimist). I would tend to believe this new (?; regurgitation of a previous approach) 'fix' just miiiiigggghhht be relaated to pending litigation. Maybe? I also think that multi-national corporations who put their share price ahead of all else (country, workers, and customers) will do the absolute minimum and stall the real, more expensive, solution.

Call me crazy.

jmmoh

Stew24

I had test driven a C7 A8 base some months earlier, but not a Grand Sport. I purchased my car some months later, over the internet, in a different state 5 hours drive away.

bjones7131

What is cost for new fluid change if you had to pay for it yourself. A guy on another post suggested 350.00, is that close?? Thanks

Sconn

That's about what my dealer wanted to charge me.

23/C8Z

I wouldn't call you crazy but I would call you uninformed.

no design flaw. It was the decision to program the converter lockup pulse with in such a way to quell vibration that DID NOT respond well to the viscosity of the fluid.

it's been an ongoing issue they've been working on since the trans came out. Not just in Corvette.

I've had 2 A8s my buddy has had 3. They all do it to varying degrees.

the newer fluid last year fixed most of it. But theres a tiny bit remaining . Slight.

my car only had around 4k miles at the flush. The reason for the TC replacement is time.. if there are too many miles on the TC the fluid change may not correct the shudder feeling. But that's a case by case basis.

I've discussed this in other threads but quick short version - the issue can be tuned out of the trans. But it requires AFM off in ecm and a procedure in the trans controller or whatever it's called. And yes, it can be done but like many I refuse to tune my car because I do t want to fight with gm if the car breaks while under warranty. If you have a tune already? Then have at it.

I'm excited they are continually attempting to correct the viscosity and eventually the right formula will make it so you cannot perceive the pulse width of the lockup.

-not a design flaw - it's a software issue corrected via tuning and or fluid formula (viscosity). Which has been done by numerous manufacturers of auto transmissions since their inception (as explained to me at Carlisle bt a Corvette engineer discussing the issue).it is not uncommon and why you've seen things like Dexron then I II III IV etc etc. Over time.

ps. I would never want a 6spd over an 8spd. I've had plenty of both and the 6spd is archaic vs the 8spd in every aspect imo.

Tinkertech

Hey 555ctsv,
When you get the fluid change please write down the Mobil1 P/N and what the dealer actually did. I'm also in the Dallas area, who is this dealer with the new fluid?

MA ZO6

Does anyone have a copy of the new bulletin? I found the following information (see attached) on the techlink site so it looks like a new way to flush the fluid along with a new fluid to solve the problem. Read the very last paragraph of the article and it talks about the 8 speed problem specifically.

John

555ctsv

I just picked up the car, paperwork says:

"Performed a trans fluid drain & fill 3 times per doc 18-NA-355"

Fluid part # said: "SYN LV HP ATF"
Also said: 19417904B
If you google "Mobil 19417904" it seems that is the part # for the bulk fluid in 55 gal drums.

I googled it and looks like it's just Mobil1 synthetic ATF.

I have only driven the car about 15 miles but it seems fine. I wasn't having any issues after we tuned out the 4cyl mode a couple weeks ago but figured it was best to get this taken care of before i dive deeper into mods

I went to Classic Chevrolet in Grapevine, TX to have this done

Gearhead Jim

There have been multiple versions of that bulletin 18-NA-355, the latest one I've seen is dated Oct 11, 2018; and is not current.
According to my source, the part number for the very newest fluid has changed, and there may be a change in the actual procedure itself, so a revised bulletin should be out. But I can't find a copy anywhere. If anyone can get a copy, please post here!

See if you can get a copy of the bulletin they used. If its dated 10-11-18, then you probably got the older (but better than previous versions) fluid, and they may have not taken any additional steps in the latest procedure.

This may not be the dealership's fault, they can only use the latest info that GM is putting out to them. The GM communications in the A8 fiasco have been a real FUBAR.