Quick answer: A shudder or “rumble strip” feeling at 25–80 mph in a Chevy Silverado or GMC Sierra with the 8-speed automatic (8L90 or 8L45) is a well-known torque converter clutch (TCC) shudder. GM’s fix is a fluid exchange with an updated Mobil 1 Synthetic LV ATF HP, typically $250–$500 out of warranty. If that doesn’t work, a torque converter replacement costs about $1,500–$3,000.
Affected vehicles
GM’s bulletin covered many 2015–2019 vehicles with the 8L90 or 8L45, including:
- Chevrolet Silverado and GMC Sierra
- Chevrolet Colorado and GMC Canyon
- Chevrolet Camaro and Corvette
- Cadillac CTS, ATS and CT6
Some later vehicles may still show similar symptoms.
Symptoms
- A vibration or shudder at light throttle, often between 25 and 80 mph, that feels like driving over rumble strips.
- Harsh or clunky shifts, especially 1–2 and 2–3.
- Shudder that is worse when the transmission is warm.
- Codes are often not stored.
The fix: fluid exchange
GM found the shudder was related to moisture in the original transmission fluid. Bulletin 18-NA-355 describes:
- A complete fluid exchange using special equipment, with the updated Mobil 1 LV ATF HP fluid.
- Several drive cycles afterward; improvement may take up to 200 miles.
- If the fluid is milky or contaminated, the cooling system must be checked first.
Costs
Typical prices, October 2026.
| Repair | Typical cost |
|---|---|
| Fluid exchange per GM bulletin (dealer or transmission shop) | $250 – $500 |
| Software update / adaptive relearn | $100 – $250 |
| Torque converter replacement | $1,500 – $3,000 |
| Transmission replacement (if damaged) | $4,500 – $7,000+ |
Under the 5-year / 60,000-mile powertrain warranty, these repairs are usually covered. Ask a GM dealer to check your VIN.
Make sure the shop uses the right procedure
A regular drain-and-fill doesn’t replace enough fluid to fix this problem, and the wrong fluid can make it worse. Ask the shop specifically whether they follow GM bulletin 18-NA-355 with the correct fluid and exchange equipment. See Transmission Fluid Change Cost for general pricing.
Is it worth fixing?
Yes. The fluid exchange is relatively cheap and fixes most cases. Left alone, a shuddering torque converter can wear and contaminate the transmission.
Related guides
Sources
- GM TechLink: TCC shudder and new Mobil 1 fluid exchange
- GM Authority: TSB seems to fix 8-speed automatic GM transmission problems