8L90: years, specs & known problems

By CarWhere Research · Updated

The 8L90 is GM's eight-speed rear-drive automatic, introduced in the 2015 Corvette and used in 2015–2018 Silverado and Sierra pickups, Camaros, Escalades and Yukons. Its best-known issue is torque converter clutch shudder at 25–80 mph, which GM addresses in bulletin 18-NA-355 with a Mobil 1 LV ATF HP fluid exchange.

GM launched the Hydra-Matic 8L90 in the 2015 Corvette Stingray and Z06 as the replacement for the six-speed 6L80. It packs four gearsets and five clutches into roughly the same space, weighs more than 8 pounds less than the six-speed, and has a 7.0 overall ratio spread. GM built it at its Toledo, Ohio transmission plant and rated it for 1,000 Nm (about 738 lb-ft) of turbine torque. The lighter-duty 8L45 shares the design.

Owners of 2015–2019 vehicles widely reported a vibration like driving over rumble strips at steady speed. GM attributed it to torque converter clutch shudder and released bulletin 18-NA-355, which calls for a full fluid exchange with blue-label Mobil 1 Synthetic LV ATF HP. Vehicles built after early 2019 left the factory with that fluid. A multistate class action over the shudder was decertified by the Sixth Circuit in 2025.

8L90 at a glance

GM Hydra-Matic 8L90 eight-speed automatic: model years
VersionModel yearsDocumented problemsRecalls
GM Hydra-Matic 8L90 eight-speed automatic2015–present20

CarWhere lists 2 documented problems and 0 NHTSA recalls for the 8L90, each with a source.

8L90 specifications

8L90: design facts (2015–present)
SpecificationValue
LayoutFour simple gearsets, five clutches (two brakes, three rotating)[2]
Gear ratios4.56 / 2.97 / 2.08 / 1.69 / 1.27 / 1.00 / 0.85 / 0.65, reverse 3.82; 7.0 spread[2]
Rated turbine torque capacity1,000 Nm (about 738 lb-ft)[1]
WeightMore than 8 lb (4 kg) lighter than the 6L80 it replaced[2]
BuiltToledo, Ohio[2]
RPO codes in shudder bulletinM5U and M5X (8L90 trucks and cars); M5N and M5T for 8L45 applications[3]
Factory fluid changeVehicles built after early 2019 breakpoints already have the HP fluid[3]

8L90 torque rating by application

8L90: published input-torque ratings (lb-ft) by model year and application
Model yearsApplicationTorque rating (lb-ft)Source
2015–presentRated turbine torque capacity1,000 Nm, per GM's SAE technical paper738[1]

"—" means we could not confirm the figure from a primary source.

Which GM vehicles have the 8L90?

GM models and model years offered with the 8L90
ModelModel yearsNotes
Chevrolet Corvette (LT1, LT4)2015–2019
Chevrolet Silverado 1500 / GMC Sierra 1500 (L83, L86, L8B)2015–2018Prior-body trucks covered by bulletin 18-NA-355
Chevrolet Camaro (LT1, LT4)2016–2019
Cadillac Escalade / GMC Yukon (6.2L L86)2015–2017
Cadillac CTS-V (LT4)2016–2019

8L90 problems and what to check

Torque converter clutch shudder (2015–2019)

Moderate

GM bulletin 18-NA-355 describes a shake or shudder during light-throttle driving between 25 and 80 mph when the transmission is not shifting, which GM attributes to torque converter clutch shudder. The correction is a dealer fluid exchange with blue-label Mobil 1 Synthetic LV ATF HP using a dedicated flush kit; GM says aftermarket exchange machines and mixing fluids will not give satisfactory results.[3]

Symptoms

  • Vibration like driving over rumble strips at steady 25–80 mph
  • Shudder that goes away when the converter clutch is fully locked or open

Check before buying

  • Drive at a steady 40–60 mph with light throttle and feel for vibration
  • Ask for proof of the 18-NA-355 fluid exchange or the build date
  • Check that the fluid used is the blue-label Mobil 1 LV ATF HP

GM program: GM Service Bulletin 18-NA-355

Harsh shifts and the 8-speed class action (2015–2019)

Moderate

A class action in the Eastern District of Michigan alleged defects in 2015–2019 GM vehicles with the 8L45 or 8L90, including harsh shifting and shudder. A Sixth Circuit panel upheld certification of a 26-state class in 2024, but the full court decertified it 9–7 in June 2025 and sent the case back to the district court. GM's 2024 information bulletin 22-NA-182 also lists the 8L90 among transmissions that can overheat when a cooler line is twisted.[4][5][6]

Symptoms

  • Clunking or harsh 1-2 and 2-3 shifts
  • Delayed engagement into Drive or Reverse
  • High transmission temperature readings

Check before buying

  • Test shifts cold and warm, including coast-down downshifts
  • Watch the transmission temperature gauge on a longer drive
  • Inspect the transmission cooler lines for twisting

8L90 issues by model

The same transmission shows up on these known-issues pages, with model-specific details.

Related GM research

Confirm a vehicle really has the 8L90.

Engine and transmission RPO codes are recorded against the VIN. The CarWhere build sheet decodes a Chevrolet VIN into the factory-ordered option codes on record — engine, transmission, axle and packages. $9.99, instant.

Chevrolet build sheet by VIN

Frequently asked questions

What vehicles have the 8L90 transmission?

The 8L90 is used in the 2015–2019 Corvette, 2015–2018 Silverado and Sierra 1500 with the 5.3L or 6.2L, 2016–2019 Camaro V8s, and 2015–2017 Escalade and Yukon with the 6.2L, among others.

How do you fix 8L90 shudder?

GM bulletin 18-NA-355 calls for a dealer fluid exchange with blue-label Mobil 1 Synthetic LV ATF HP after a shudder test confirms the torque converter clutch is the cause.

Is there a recall on the 8L90?

No NHTSA safety recall covers the 8L90 shudder. GM handled it through service bulletin 18-NA-355, and a related class action was decertified in 2025.

How much torque can the 8L90 handle?

GM's SAE paper rates its turbine torque capacity at 1,000 Nm, about 738 lb-ft.

What is the difference between the 8L90 and 8L45?

Both are GM eight-speed automatics of the same design; the 8L90 is the heavier-duty version for V8s, while the 8L45 is used with four-cylinder and V6 engines such as the Colorado's 3.6L.

Sources

Ratings are GM-published figures as cited; descriptions are CarWhere’s own summaries of the sources below. Repair costs appear only where a source states them and vary by shop and region.

  1. SAE Technical Paper 2014-01-1721: GM's new eight-speed rear-drive automatic (8L90) — SAE International
  2. New 8-Speed Enables Quicker, More Efficient Corvette (GM press release, Aug. 2014) — Chevrolet press release (reprinted by Corvette Action Center)
  3. Service Bulletin 18-NA-355: Shake and/or Shudder During Light Throttle Acceleration Between 25 and 80 MPH (Aug. 2019) — General Motors (via NHTSA)
  4. GM Wins Victory as Appeals Court Decertifies Transmission Lawsuits — Claims Journal
  5. GM Must Face Big Class Action Over Faulty Transmissions — Claims Journal
  6. Service Bulletin 22-NA-182: Information on 6L80, 6L90, 8L90, 10L80, 10L90, 10L1000 Vehicles With Harsh Shift, Shudder, Surge, Stall, Overheating (March 2024) — General Motors (via NHTSA)

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