The 8L90 is GM’s eight-speed automatic from the 2015 model year, and the 10L80 is the ten-speed GM introduced in its full-size trucks and SUVs around 2019, developed jointly with Ford’s 10R80. The 10L80 has more ratios, a deeper first gear and smaller steps between gears, and it replaced the 8L90 in many trucks. Both have had shift-quality complaints addressed by software, and neither swaps into a vehicle built for the other without changes to wiring and programming.
8L90 vs 10L80 at a glance
| 8L90 | 10L80 | |
|---|---|---|
| Gears | 8 | 10 |
| Gear ratios | 4.56 / 2.97 / 2.08 / 1.69 / 1.27 / 1.00 / 0.85 / 0.65 | 4.70 / 2.99 / 2.15 / 1.77 / 1.52 / 1.28 / 1.00 / 0.85 / 0.69 / 0.64 |
| Introduced | 2015 model year | Around 2019 in full-size trucks and SUVs |
| Design | GM eight-speed | Developed jointly with Ford (Ford builds the 10R80) |
What ten speeds change
With ten ratios, the transmission can keep the engine closer to its most efficient speed and skip gears when it makes sense. Owners mostly notice smoother towing and lower highway rpm; some notice frequent shifting at low speed. See 10R80 vs 10L80 for how GM’s and Ford’s versions differ.
Known issues
- 8L90: torque converter shudder at cruise and harsh shifts, often improved with an updated fluid and software; see 8L90 problems.
- 10L80: harsh or delayed shifts and shift flare, often improved with adaptive relearn and software updates; see 10L80 problems.
Which is better?
For a used truck, a well-maintained example of either with its updates applied is a better bet than chasing the gear count. For towing, both work well within the truck’s rating; the 10L80’s closer ratios help on grades. Check the service history and test-drive for shudder and harsh shifts.
Maintenance
Both are sensitive to fluid type and condition. Use the fluid GM currently specifies for your transmission, which has changed on some models through service bulletins, and check the level with the procedure for your vehicle, since neither uses a conventional dipstick on most trucks. After any repair or fluid service, an adaptive relearn helps the transmission shift smoothly again.
How to tell them apart
The vehicle’s service parts label lists the transmission option code, and the model year narrows it down. Some trucks were offered with either depending on engine, so check rather than assume; see what transmission do I have?
Replacement units we list
- RoadReady Chevy 8L90: $4,399.00
- StreetMonster Chevy 8L90E: $3,999.00
- RoadReady Chevy 10L80: $4,299.00
Each includes a torque converter. Browse 8L90 and 10L80 transmissions, and see 6L80 vs 8L90.
More guides: how long an 8L90 lasts.
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