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If you own a 2015-up Silverado, Sierra, Tahoe, Yukon, Escalade, or Corvette, you have one of GM's two big rear-wheel-drive automatics: the 8-speed 8L90 (and its lighter-duty cousin the 8L45) or the 10-speed 10L90 (and the 10L80 / 10L1000). They look similar, they bolt to the same LS and LT V8s, and the parts catalogs overlap — but the 8L90 earned a rough early reputation while the 10-speed is the unit GM and Ford co-developed to replace it. Here is the honest comparison.
Side-by-Side Specs
| Spec | 8L90 | 10L90 |
|---|---|---|
| Forward gears | 8 | 10 |
| Introduced | 2015 (Corvette, trucks) | 2017 (Camaro ZL1, then trucks 2019) |
| Max input torque (approx) | ~664 lb-ft | ~664 lb-ft (10L90); 10L1000 higher |
| 1st gear ratio | 4.56 | 4.70 |
| Top gear ratio | 0.65 (overdrive) | 0.63 (overdrive) |
| Clutch packs | 5 clutches, 2 brakes | 6 clutches |
| Fluid | DEXRON ULV | DEXRON ULV |
| Fluid capacity (dry) | ~10.6 qt | ~11.6 qt |
Both use DEXRON ULV (ultra-low-viscosity) — do not pour DEXRON VI or HP into either one. The thinner ULV fluid is part of why these transmissions are fuel-efficient and also part of why they are sensitive to fluid condition.
Find DEXRON ULV fluid
Known Problems — 8L90
The 8L90 (and 8L45) launched with a real reputation for harsh, clunky shifts — the infamous "Chevy shudder." Most of it traces to two things:
- Torque-converter shudder. A lockup clutch shudder felt as a vibration around 30-50 mph under light throttle. GM issued multiple TSBs (the well-known fluid flush bulletin) calling for a flush to the newer Mobil-formulated ULV fluid. Many trucks were fixed by a proper triple flush; the worst needed a converter.
- Valve body / accumulator wear. Hard 1-2 and 2-3 shifts and flares often come down to valve-body bore wear and worn solenoids. Sonnax sells targeted bore-repair kits and updated solenoids for the 8L90.
If you have an early 8L90 that bangs and shudders, the first move is a complete fluid exchange with current-spec ULV, not a teardown. A lot of these are fluid problems wearing a transmission costume.
Browse 8L90 valve body and solenoid parts
Known Problems — 10L90
The 10-speed is the better-behaved of the two, but it is not bulletproof:
- Harsh shifts and hesitation on early builds. Like Ford's shared 10R80, early 10-speeds had software-driven shift-quality complaints addressed by TCM reprogramming. Get the latest calibration before condemning hardware.
- Torque-converter shudder, again. The 10-speed can shudder too, and the fix path is the same: correct ULV fluid and, if needed, a converter.
- Wave plate / clutch wear on hard-driven trucks. High-torque towing and tuned trucks can chew clutches; the 10L1000 is the heavy-duty version built to take more.
The 10L90's extra two ratios keep the engine in its sweet spot more often, which means less lugging and, in practice, less heat — the thing that kills these transmissions.
Which One Should You Want?
If you are shopping a used truck and have the choice, the 10-speed (10L80 / 10L90) is the one to buy. It shifts smoother once calibrated, holds gear better for towing, and benefits from being the design GM intended to keep. The 8L90 is perfectly serviceable once its shudder is sorted, but it carries the early-production baggage.
If you are rebuilding: both are rebuildable, both have strong aftermarket support (Sonnax, Raybestos, Alto), and both reward an upgraded torque converter and a deep pan with extra fluid capacity for cooling. The single biggest reliability upgrade on either is a quality auxiliary transmission cooler if you tow.
Browse transmission coolers
8L90 and 10L90 Parts — Ships Same-Day
Rebuild kits, frictions, steels, solenoids, valve-body components, and converters for the 8L90, 8L45, 10L80, and 10L90. gearboxinsider.com ships same-day before 2pm Eastern with free shipping on every order.
Shop Gearbox Insider →FAQ
Are the 8L90 and 10L90 interchangeable?
They share a bellhousing pattern with GM V8s, but they are not a plug-and-play swap for each other — case length, output, TCM calibration, and wiring differ. A swap is a project, not a bolt-in.
What fluid do both use?
DEXRON ULV (ultra-low-viscosity). Using a heavier fluid like DEXRON VI causes shift-quality problems and can trigger shudder. Always confirm ULV.
Is the 8L90 shudder a death sentence?
No. The majority are resolved with a proper multi-pass flush to current-spec ULV fluid per GM's bulletins. Only the worst cases need a torque converter. Try the fluid fix first.
Which lasts longer for towing?
The 10-speed, because it keeps the engine in a better rpm band and runs cooler under load. Either one lives much longer with an added cooler and disciplined fluid changes.