Quick answer
Dexron is GM's licensed ATF family. Mercon is Ford's. Both have gone through multiple generations - the current GM spec is Dexron VI (mineral) and Dexron HP (high-performance for 10L80/10L90); current Ford specs are Mercon LV and Mercon ULV. They are tuned for different transmission clutch designs and are not interchangeable in most modern applications.
Dexron family generations
- Dexron II / IID - 1973-1990s, mineral oil with friction modifier. Used in TH350, TH400, 700R4.
- Dexron III/H - 1993-2005, refined mineral with improved oxidation. Used in 4L60E, 4L65E, 4L80E.
- Dexron VI - 2005+, low-viscosity synthetic blend. Mandatory for 6L80, 6L90, 6T70, 6T75 transmissions. Backward-compatible with older Dexron versions.
- Dexron HP - 2017+, higher-viscosity synthetic for GM 8L90, 10L80, 10L90.
Mercon family generations
- Mercon - original 1987 Ford spec; obsolete.
- Mercon V - 1997+, used in 4R70W, 5R55W, AX4N.
- Mercon LV - 2008+, low-viscosity for 6R60, 6R80, 6F35, 6F50 transmissions.
- Mercon ULV - 2017+, ultra-low viscosity for 10R60, 10R80, 8F35.
- Mercon SP - 2003+, synthetic for 5R110W TorqShift diesel.
Side-by-side use
| Vehicle | Fluid |
|---|---|
| 2007+ Silverado / Sierra / Tahoe (6L80) | Dexron VI |
| 2017+ Silverado / Sierra (10L80, 10L90) | Dexron HP |
| 2008+ F-150 (6R80) | Mercon LV |
| 2017+ F-150 (10R80) | Mercon ULV |
| 4L60E / 4L65E (1993-2014) | Dexron III or VI (backward compatible) |
| 4R70W / 4R75W (1997-2008) | Mercon V |
Are they interchangeable?
Older Dexron III and Mercon V are sometimes considered "loosely interchangeable" by aftermarket fluid blenders, and many universal ATFs claim to meet both. In practice, the friction modifiers are different and shift quality often degrades after a cross-fill.
Modern Dexron VI / HP and Mercon LV / ULV are fundamentally different fluids - never mix them. Each transmission family is engineered around one fluid spec.
Common mistakes
- Using Dexron VI in a Ford 6R80. Causes lockup converter shudder and shift flare.
- Using Mercon V in a GM 6L80. Wrong viscosity and friction profile - shift quality degrades quickly.
- Topping off with "Dexron/Mercon universal" in a 10R80 or 10L90. These transmissions require the licensed ULV or HP fluid; "universal" fluids do not meet either spec.
- Skipping the OEM-licensed fluid to save money. A $3,000-6,000 transmission rebuild costs more than a lifetime supply of the correct ATF.