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Dexron III transmission fluid versus Dexron VI transmission fluid

Dexron III transmission fluid versus Dexron VI transmission fluid

The Dexron series of transmission fluids was introduced by GM in 1967 as Dexron B. The fluid went through several revisions C, D, and E before being replaced by Dexron-III (F) in 1993. Dexron-III(F) was build on Group 2+ base oil and an additive package.

Dexron-III(F) was designed to provide better friction stability, more high-temperature oxidation stability, and better material compatibility. Unfortunately, Dexron-III(F) wasn’t as durable and didn’t provide enough shear stability or prevent enough oxidation prevention.

GM’s upgrade to Dexron III(G) in 1998 and then to Dexron III (H) in 2003. The (H) fluid had an improved  additive package and an updated friction modifier and more oxidation protection. It’s still built on a base 2 oil.

Dexron VI is introduced

Dexron VI (J) was introduced in 2006. Dexron VI has a lower viscosity than previous Dexron fluids but also has lower shear which results in a more stable fluid with lower final viscosity. The lower viscosity improved pumping efficiency. Dexron VI is regarded as a Full Synthetic Automatic Transmission Fluid, although the base oil is not listed.

Dexron III licensing is eliminated

GM stopped licensing Dexron III in 2011. The name



Dexron III cannot be made or sold.  However, oil blenders still sell an ATF III (H) product to use in older transmissions that were designed to run on Dexron III. It’s the same transmission fluid as Dexron III but can’t be labeled as Dexron due to the lack of licensing, which is why the label only states ATF III (H). These fluids are not endorsed by GM.

Dexron VI is backwards compatible with Dexron-III(H) and Dexron-III(G) fluids only.

DEXRON-VI(J) is introduced in 2005

Dexron VI(J) was developed in a joint venture between GM and Ford. Ford calls their version Mercon Low Viscosity (LV) and GM calls theirs Dexron VI(J). Dexron VI is rated for 100,000 miles for normal driving and 80,000 miles for severe service.

dexron VI
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