We're all all right there with you, hoping the same thing. :happy0180:

I know right ! I use to never let it go in 4 cylinder mode on highway driving because that was when it was the worst and now I can’t even tell when it drops into v-4 mode it’s seamless.

So I'm having a similar issue with mine. Around 1700 rpm and 78mph the car bucks a lot. Rpm fluctuates a bunch as well. Also does this around 60-75mph. It's almost like my converter isn't locking up fully and it bucks the car while driving.

Have you brought it in for the fluid flush yet?

Not yet. But will be soon. Is there also a tcm reflash that has to be done? If so that could be a problem.

I had the same issue as you. First step was a fluid change and putting 500 miles on it. No luck! Then it was taken in for a TC exchange, lower speed shudder was resolved by this, but anything above 70 and it shook like crazy. About a month ago I did another type of flush. Since I’ve done this there has been a dramatic improvement. I’m hesitant to say it’s gone only because I don’t want to jinx myself lol

Well, I've been noticing this shudder in mine for a while and stumbled in here. I too thought it was just the roads, but wasn't convinced the more I drive. Called the dealer and scheduled to drop it off tonight ...

Well, mine is a 2018 SS with the A8 and is having this exact same problem. Hi everyone. I'm surprised this thread/issue started in 2016 and still it is present on 2018 vehicles; quite disappointing to say the least.

Anyhow, it started when it had about 8,500 miles more or less, to the point it started to get more apparent, to stop thinking about road conditions and stupid things like that. I take it to the first flush at 9,300 miles to a Chevrolet dealer in Broward County, FL, and they got it done no problem. The adviser I work with is more than knowledgeable and helpful so to me this is clearly not the issue as he always goes well beyond what I can expect. Anyways, I was told to wait about 200 miles and if so bring it in, but I thought of waiting a bit more and the issue never went away but simply was felt less for a few miles and went back. Today, I take it back for them to do the diagnostics required by GM and apparently everything came back normal as I said it would.

The issue in my car only comes up after driving on the highway for about 10-20 minutes or more, and around 1,250 rpms at 35-65 mph and then at high speed it is even harder when I let go off the gas and simply push the pedal to keep it in speed at around 1,500-1,750 rpms (awful feel right there). This is not that harsh in the mornings as the drive is not as long as in the afternoon. At this point, as the data does not show anything to support needing a new TC (I'm not looking to have it replaced but simply get the car fixed and have it behaving as a 1-year-old car) I'm simply at a standstill as GM doesn't approve the replacement because of the data, so tomorrow apparently I am supposed to pick it up the same way I dropped it off. Obviously to me this is not acceptable as I should not have to even think of taking a risk of doing another flush myself and with the limited time I have.

Can anyone help out here, especially from GM?

What TSB did the dealer perform on your car? Also diagnoses is NOT REQUIRED for the most recent TSB (18-NA-355) issued by GM. Take your car to a different dealer if that’s what they’re telling you.

Apparently this same one was the one done last time, but apparently the filter was not replaced. They will do it again and replace the filter per my request and the service adviser and the technician both agreed it should help as it might still have some residue in the converter. After this attempt, it will be either trying a different dealer or figure something else out.

A few months after buying the car, I had the rubbing noise coming from the differential, and after having the flush done it got worse. I literally had to buy the correct fluid (also referenced in the manual) and do it myself, to then have it corrected. I don’t like the idea of having to do the same with a transmission which personally I don’t like working with.

Same result here had mine done 1.5month ago car only had 200miles on it. For sure GM has been tinkering with ATF formulas. Perhaps tuning ECM and v4/8 algorithm. Have been looking at people complaining and year car they have and for sure early ones have more issues. So mine is good so far with formula 8/2019

Got mine done beginning of September. So far so good.

ive put a couple thousand miles on my car since the new flush from earlier this year and its been solid so far.

Just did the flush on my 2017 v6 rs a couple of days ago and it seems to be o.k...but, i still have a "clunking"sound when the car down shifts between 3rd and first..anyone know what this is??,,and for the people who are having their dealership refuse to change the fluid because they can't replicate the issue go back a few post and print out the tsb 18-na-355 it states clearly that all that is needed is a customer complaint, they are not required to duplicate the problem. I'm from canada and the fluid part # up here is 19418066, does anyone know if this is the same mobile 1 fluid they are using in the U.S. ?:noidea: