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Guest curtis6234

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The fluid specification for Dexron-VI was introduced in 2005, and was first used as the GM factory-fill automatic transmission fluid for model year 2006. All Dexron-III licenses expired permanently at the end of 2006, and GM now supports only Dexron-VI fluids for use in their automatic transmissions,[3] although fluids asserted by their manufacturers to meet Dexron-III standards continue to be sold under names such as Dex/Merc. These fluids are not regulated or endorsed by GM.[4]

Dexron VI is of a slightly lower viscosity when new compared to the prior Dexron fluids (a maximum of 6.4 cSt at 100°C for Dexron VI and 7.5 cSt for Dexron III), but the allowed viscosity loss from shearing of the ATF during use is lower for Dexron VI, resulting in the same lowest allowed final viscosity for both Dexron III and VI (5.5 cSt).[5] The lower viscosity is intended to gain improvements in fuel economy by lessening parasitic drag in the transmission. Since Dexron VI is not allowed to thin out (lower its viscosity) as much as Dexron III during use, it requires the use of higher-quality, more shear-stable (less prone to thinning while in use) base oils.[4] The current GM specification that defines the fluid is GMW16444, which superseded the original specification, GMN10060."

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Dexron III fluid is still available.  GM does not support or license it any more, as Dexron VI has replaced it.  Dex VI is a semi-synthetic fluid needed for the newer 6-speed automatics, and retrofits all the way back to 1949, as Dex III did.


Dexron III is now "All Makes" ATF, in many brands of fluid.  Have to read the back of the bottle to see that GM is the main application for the fluid, as Dexron III was.


Your judgment call. There is a price difference.  Dex VI should last longer, I suspect.   Either way, as long as it's "Dexron III" or "Dexron VI", it should be fine.



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