I would recommend getting the fluid changed. The Range device, contrary to what some believe here, does nothing to alter how the transmission shifts. The new fluid makes a major change in how smooth the transmission shifts.

The reason I went ahead and changed my fluid after the Range device was installed was that I already had over 60,000 miles on the car and was starting to develop a very mild shutter. That went away after the flush. I now leave the Range device in at all times. I thought it was beneficial and it was due for a change anyway.

I think the TC clutch still functions even with the range but just not as active, could be wrong but don't think so. If my assumption is correct the fluid change would be a good thing. If GM want do mine under warranty even though I have no issues and use the range device I would pay the 380.00 for piece of mind. The local chevy dealers in my area are clueless on the TC and Mag Ride upgrade and famous Warble problem so little hesitant to have them do anything except free oil changes and watch like a hawk. We keep hearing about a TSB coming in 2019 with a TC fix but not holding my breath.

This is all not totally true. I have had a Range in my '16 A8 since new and now at 12K miles my torque converter is toast. Had the triple flush already, as expected had no effect on the issues. Waiting until I get 200 miles on it to return for another torque converter to be installed. So it's not solely the V4 mode causing the failures. At least not in my case

Agree that TC is still active with range but not as much. They quit doing the 3flush and now do a one flush, (so I am told or read) and blow out the lines and put in the NEW fluid. We will see what the new fix brings that is coming. Good luck with fix.

There are other causes of shudder besides a bad converter clutch but because this is such a common issue with 8L45/8L90 equipped vehicles very few dealer techs actually follow the TSB to test that the clutch is at fault. If there is another problem with power delivery, the new converter won't fix the problem. GM's own TSB calls for the tech to test the converter in all three modes (command unlocked, command locked, and normal) and if the shudder is still present in the unlocked or locked modes then the fault lies outside the converter lockup clutch. It is also possible that your converter clutch was simply defective from the start and neither magic fluid nor protection from the clutch eating AFM behavior would have made a difference.

Even without AFM, there are going to be transmission defects in normal production but this combination of AFM plus "squashed converter" has created such a huge issue that every problem that in any way matches the converter clutch shudder will be blamed on it by the tech resulting in a longer path for the customer to get the problem actually resolved if it isn't the issue addressed in the multiple TSBs that continue to be released as GM searches for a cheap way to bury this design fault.

TSB's, Ranges, and ATF's
Overall, my A8 does not have the shudder issue. But it did have some seemingly rough shifting patterns in some situations. It also has the usual annoying hesitation/hunting caused by the AFM/V4 mode.

TSB's - I was holding off with the Range until I heard more details about the new 18-NA-355 TSB. With what is known so far, that TSB turns out to be limited to a fluid change (again) with (another) new fluid part number. I was hoping for a GM reprogram to avoid V4 except when in ECO/Weather like the M7. Sigh....

Range - So I acquired a Range and put it in today. My experience is much like the others - very noticeable improvement in hesitations on throttle tip-in and overall much smoother operation. As observed by many - the range device offers distinct improvements. Importantly, I could now separate tranny shift issues from AFM problems! With the Range, there are still a couple of minor blips in my A8, such as a sometimes noticeable downshift when arriving at a stop sign/light. But this problem was much worse when new.. which leads me to ATF.

ATF - My A8 has had 2 separate DIY fluid changes about 1000 miles apart with Mobil 1 LV ATF HP as recommended in the GM TSB 16-NA-175. (Mobil part number 122210). The fluid level check was carefully followed each time. Each change smoothed out the shifting and smoothness of the tranny.
I may be wrong, but I do have this opinion - - Changing out the original factory fluid with the Mobil 122210 LV ATF HP or the newer version (whatever that number may be) does no harm and can do quite a bit of good. The 'good' part is the possibility of smoother shifting operation and a preventative measure against future shudder problems. Even if the shifting is unchanged, the fresh fluid would seem to be a wise move given the A8 problems.
I will be considering a THIRD change if the reports for this 'new' fluid are positive.
If you have ever watched the video showing what it takes to do a TC/Tranny replacement, then you may have shuddered more than the A8 ever has!!! You just don't want that to have to happen.

You mentioned 2 DIY fluid changes, did u do it or someone else, care to share cost. Thanks

I did the changes - about $120 for fluid, filter, and gasket.

My Range device arrived a couple of days ago and I plugged it in right away to confirm the version number. Got to take her out for a ride today in our unseasonably warm 45 degree sunny day. Went about 20 miles on local and expressway traffic. Ran great and it did seem to upshift and downshift more smoothly. No error codes. Happy camper.

My Range arrived yesterday and I installed it today. I drove the car to work and back and really didn't feel any difference. I did watch and I did see that it never went into V4 mode.
I had a 2014 M7 and I maybe put it in ECO mode half a dozen times in 4 years, so I feel like why should my A8 go into V4 every time I lift the throttle?

Just out of curiosity, has anyone pulled the Range out while driving?

Why in the world would you want to do that ? I have to believe that it cant be good ..
Do you shut your laptop down by pulling out the battery ...?
Dave

I can't think of a good reason to pull it out while driving but it shouldn't hurt anything.

The earlier version sometimes caused a CEL at startup (loss of communications between ECM and TCM DTC set) and Range set it up so that if you unplugged and plugged the Range in while the car was running it would clear the CEL. When I had the earlier version in my Z06 I used an OBD II extension cable with integrated power switch and turned the Range on after the car was running, a lot of us used that method to avoid the communications error but it isn't needed with the current Range software revision.

What year is your car? My 2018 has nearly seemless transitions between V4 and V8 mode.

Right , but if you unplug a range that has NOT tripped the CEL because of loss of communication with the CAMBUS you surely will cause a CEL
With the old range device it was not recommended to switch it off or unplug it to clear a CEL while running , what the firmware did after a few revisions was if you shut the car off and then restarted it it would clear any CEL tripped as part of the boot up .....

Where are you folks buying these?

Directly from Range , that way you know you have the latest firmware and you are not buying from some unauthorized seller

They ship fast !!
Dave

I will be looking into buying mine when it gets warmer around Chicagoland.