The right transmission fluid is the one your transmission’s maker specifies, usually printed on the dipstick, in the owner’s manual or on the fill cap. GM automatics such as the 4L60E, 4L80E and 6L80E use Dexron VI, which GM introduced to replace Dexron III and approves for older transmissions that called for it. Ford uses Mercon V in older transmissions and Mercon LV in most later ones, and Chrysler and Ram transmissions such as the 48RE and 68RFE use ATF+4.
Transmission fluid by transmission code
| Transmission | Specified fluid |
|---|---|
| GM 4L60E, 4L65E, 4L80E | Dexron VI (replaces Dexron III) |
| GM 6L80E, 6L90E | Dexron VI |
| GM 10L80 and Ford 10R80 | Ultra-low-viscosity fluid: Dexron ULV (GM) and Mercon ULV (Ford) |
| Allison 1000 | An Allison-approved fluid or the Dexron fluid GM specifies for the truck |
| Ford 4R70W, 4R100, E4OD | Mercon V |
| Ford 6R80, 6R140 | Mercon LV |
| Dodge and Ram 46RE, 47RE, 48RE, 545RFE, 66RFE, 68RFE | ATF+4 |
Specifications can change with model year and service bulletins, so confirm the fluid in your owner’s manual. The 8L90, for example, has GM service bulletins that call for an updated fluid; see 8L90 problems.
Dexron III vs Dexron VI
Dexron VI is GM’s current specification and is more resistant to breaking down than Dexron III. GM approves Dexron VI for use in transmissions that originally specified Dexron III, so it is the usual choice for older GM automatics too. Dexron III is no longer licensed by GM.
Mercon V vs Mercon LV
Mercon LV is a lower-viscosity fluid developed for Ford’s newer six-speed and later transmissions. Ford does not list Mercon V and Mercon LV as interchangeable, so use the one your transmission specifies: Mercon V for the 4R70W, 4R100 and E4OD, and Mercon LV for transmissions such as the 6R80 and 6R140.
ATF+4
ATF+4 is Chrysler’s specification for its automatics, including the Dodge and Ram RE and RFE transmissions. It replaced the earlier ATF+3, and Chrysler warns against substituting generic fluids in transmissions that call for ATF+4.
Can you mix transmission fluid?
Topping up with a different type than the one specified can change shift feel and friction behavior and, in some transmissions, cause shudder or slipping. Use the specified fluid, and if the wrong fluid went in, a fluid exchange back to the correct type is the safe fix. “Multi-vehicle” fluids exist, but check that the bottle lists your exact specification.
Related guides
How to change transmission fluid · how to check transmission fluid · transmission fluid color · how often to change transmission fluid · 4L60E fluid capacity. Replacing the transmission instead? Find it by code on our transmissions page.
More guides: transmission fluid chart by code.
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