GM 6-Speed vs 8-Speed vs 10-Speed Compared

GM evolved from 6-speed (6L80) to 8-speed (8L90) to 10-speed (10L80) automatics. Here's the comparison and what each generation brought.

Quick overview

6L80 (2006-2017):

8L90 (2015-present):

  • 8-speed automatic
  • Replaced 6L80 in light trucks
  • Read our 6L80 vs 8L90

10L80 (2017-present):

  • 10-speed automatic
  • Co-developed with Ford 10R80
  • Latest evolution

Gear ratios

6L80:

  • 1st: 4.03
  • 2nd: 2.36
  • 3rd: 1.53
  • 4th: 1.15
  • 5th: 0.85
  • 6th: 0.67

8L90:

  • 1st: 4.56
  • 2nd: 2.97
  • 3rd: 2.08
  • 4th: 1.69
  • 5th: 1.27
  • 6th: 1.00
  • 7th: 0.85
  • 8th: 0.65

10L80:

  • 1st: 4.70
  • 2nd: 2.99
  • 3rd: 2.15
  • 4th: 1.80
  • 5th: 1.52
  • 6th: 1.28
  • 7th: 1.00
  • 8th: 0.85
  • 9th: 0.69
  • 10th: 0.64

Result trend:

  • More gears = more refinement
  • Lower 1st gear = better acceleration
  • Wider spread = better MPG potential

Strength comparison

Stock capacity:

  • 6L80: ~470 ft-lb
  • 8L90: ~600 ft-lb
  • 10L80: ~700 ft-lb

With HD upgrades:

  • 6L80: 650+ ft-lb (Sonnax billet)
  • 8L90: 750+ ft-lb (HD parts)
  • 10L80: 850+ ft-lb (developing)

Read our Sonnax explained

Applications

6L80:

  • 2007-2014 Silverado/Sierra 1500
  • Tahoe/Yukon (2007-2014)
  • Camaro Z28 (early)
  • Corvette (early C6)

8L90:

  • 2015-2018 Silverado/Sierra 1500
  • 2015-2019 Tahoe/Yukon
  • 2014+ Corvette Stingray
  • ZL1 Camaro

10L80:

  • 2019+ Silverado/Sierra 1500
  • 2020+ Tahoe/Yukon
  • ZL1 Camaro (later)
  • Newer applications

Read our how to identify your transmission

Common failures

6L80 famous failures:

8L90 issues:

  • TCC PWM shudder (same as 6L80)
  • Read our 6L80 shudder fix
  • Hard shifts at lockup
  • Mechatronics wear

10L80 emerging issues:

  • Too new for full failure pattern
  • TCC PWM concerns developing
  • Mechatronics wear concerns

Read our transmission warning signs

Maintenance differences

6L80:

  • Dexron VI standard
  • Drain pan + filter common
  • Aux cooler standard

8L90:

  • Dexron VI HP (specific to 8-speed)
  • Mechatronics significantly more complex
  • Premium fluid mandatory

10L80:

  • Dexron VI ULV (ultra-low viscosity)
  • Sealed-for-life marketing (don't believe)
  • Premium fluid critical
  • Read our transmission fluid types

Rebuild costs

6L80:

  • DIY: $1,000-1,800
  • Shop: $2,500-4,500
  • Most aftermarket mature
  • Read our 6L80 rebuild cost

8L90:

  • DIY: $1,200-2,000
  • Shop: $2,800-5,000
  • Mechatronics expensive
  • HD parts developing

10L80:

MPG and performance

6L80:

  • Adequate MPG for era
  • Smooth shifts
  • Capable performance

8L90:

  • 1-2 MPG improvement vs 6L80
  • Smoother shifts
  • Better acceleration
  • Read our 6L80 vs 8L90

10L80:

  • 1-2 MPG improvement vs 8L90
  • Even smoother shifts
  • Quickest acceleration
  • Highest gear count complexity

Aftermarket support maturity

6L80:

  • Most mature aftermarket
  • Sonnax billet everywhere
  • Read our 6L80 wave plate
  • HD options widespread

8L90:

  • Aftermarket strong
  • Sonnax expanding
  • HD options developing
  • Service mature

10L80:

  • Aftermarket emerging
  • Limited HD options
  • Service developing
  • Mostly OEM-only currently

Which to choose (engine swap context)

LS swap into older vehicle:

Modern 1500 swap (after 2007):

  • Use whatever came with engine
  • Don't downgrade

Performance build:

  • 6L80 with HD parts (most support)
  • Or 4L80E for HD/race (different family)
  • Read our 4L80E vs 6L80

Operating tips

All three benefit from:

Avoid:

  • Tow in highest gear
  • Ignored temp warnings
  • Cheap fluid

Diagnostic differences

6L80:

8L90:

  • Modern protocols
  • Most data accessible
  • Standard OBD-II

10L80:

  • Latest protocols
  • Sometimes needs latest scan tool
  • Most parameters available

Cost of ownership over time

6L80 (older vehicles):

  • Lower entry, possibly higher service cost
  • More aftermarket = cheaper rebuilds
  • Service: $200-400 per pan-off

8L90 (mid-age vehicles):

  • Mid entry
  • Service: $300-500 per pan-off
  • HD parts available

10L80 (newest vehicles):

  • Higher entry
  • Service: $400-700 per pan-off
  • Limited HD parts

Common myths

Myth 1: More gears always better

  • Reality: marginal MPG gain
  • More complex = more failure modes
  • Mechanical reliability trade

Myth 2: New = better

  • Reality: 6L80 has most refined aftermarket
  • 10L80 still developing
  • Pick based on application

Myth 3: All GM modern trans same

  • Reality: each generation distinct
  • Don't swap parts across
  • Verify before service

Read our identify your transmission

Need 6L80, 8L90, or 10L80 parts? Shop our complete catalog. Rebuild kits, Sonnax HD upgrades, mechatronics components. Free shipping over $70.

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