Mechanics of the OT, I need your help with my transmission

Thanks for sharing the detailed breakdown — that’s helpful in understanding what you’re dealing with. Based on the symptoms you described (sputtering/skipping when shifting, loss of power over 50 mph, gas pedal unresponsive, engine revving in drive but not moving), you’re likely dealing with a serious transmission issue, especially with a 2017 Tahoe at 164,000 miles. Here’s a breakdown of what could be going on and how to proceed:

Possible Causes
Transmission Slipping or Failure:
If the engine revs but the vehicle doesn't move, that’s a classic sign of internal transmission failure.
Could be a failed torque converter, clutch packs, or solenoid pack.
Electronic Throttle or Transmission Control Issues:
A malfunctioning throttle position sensor (TPS) or transmission control module (TCM) could cause loss of acceleration and erratic shifting.
However, if the vehicle revved but didn't move in Drive, it's more mechanical than electronic.
Fluid Condition:
Even if the level looks okay, burnt or dirty fluid indicates internal wear.
Smell the fluid — does it smell burnt? Is it dark brown or black?
About Shudder Fixx / Additives
Shudder Fixx by Lubegard is designed to treat torque converter shudder, a common issue with GM 6-speed and 8-speed transmissions. It can be effective if:

You’re dealing with torque converter shudder specifically (feels like driving over rumble strips when accelerating).
Your transmission still has some function left.
BUT — it’s a band-aid, not a repair. In your case:

If the transmission completely disengaged, meaning it revs and doesn't move at all, the additive is unlikely to solve it.
It's harmless to try once the shop opens, but don’t expect it to restore full function.
What to Do Next
Wait for a proper diagnostic from the transmission shop.
Ask them to scan for transmission codes — they can tell you whether it's internal wear or a sensor/module issue.
Be prepared that at 164K miles, a transmission rebuild or replacement may be needed, especially if the fluid hasn’t been changed regularly.
Cost Expectations
Transmission rebuild: ~$3,000–$4,500
New or remanufactured transmission: ~$4,000–$6,000
Used transmission with installation: ~$2,000–$3,000 (riskier)
Final Thoughts
It sounds like your transmission is likely at the end of its life — not uncommon for high-mileage GM SUVs of that era, especially if the 6L80 or 8L90 transmission hasn't been serviced regularly. Shudder Fixx might help if the issue is minor, but don’t count on it reviving a failing trans.

Let me know what the shop says when they run diagnostics — happy to help you make sense of the quote or options they give. And… Geaux Tigers indeed.

did you ask Grok or ChatGBT?

It’s been shuttering for a long time and you didn’t know what it was.

165k on a 2017 Chevy is outstanding this day and age be happy you got that much

Change transmission fluid AND filter every 55,000-60,000 in a ford and or a Chevy. Do NOT let them talk you into a flush and fill.

It’s too late for yours. Replace the trans or trade it in.

Does it move after it’s been shut off/ cooled off?

Sounds like you’ve had a serious transmission failure. It’s shot. You have two choices.

1. Allow the transmission shop to rebuild your transmission. That’s a crap shoot on whether or not they know what they’re doing. Make sure you get a very detailed description of the warranty they offer.

2. Buy a transmission. If you go to the dealership, you’ll most likely have the option of buying either a brand new or reman transmission. The remain will cost less. You’ll at least have the peace of mind of knowing this transmission was built (or rebuilt) to manufacturer specifications with OEM parts and is installed by GM trained technicians to GM specs. But again, make sure you get all the warranty details. Your other option is to buy an “aftermarket” new or rebuilt transmission from the transmission shop. This transmission most likely will not have OEM parts, nor built by to GM standards. So, another crap shoot.

Good luck.

Your transmission is burned up. It won’t get out of second gear. It’s a goner.


Sorry.

Just trade in a 2018 Chevy Silverado with 135k. Transmission started to act up so it was time for it to go while I could unleash it.
Get ready though bc ur trade in value won’t be worth anything. Especially if it’s acting up that bad. Those Chevy transmissions it isn’t if it will go out it’s when…….

quote:

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2017 Tahoe with 164k miles

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You got 14k more than normal with that transmission.

Your torque converter is trash and sent metal shavings through your transmission. It is toast and you need a new one.

ETA: make sure to get a reman with a good warranty and upgraded torque converter.

Ignition coils are going out. Change the coils and new plugs and you'll be good