The 1947 - Present Chevrolet & GMC Truck Message Board Network - Transmission fluid

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Transmission fluid - FYI

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Quote:

Originally Posted by Slammed72blazers (Post 5347533)

what type of oil should i use for my Th350 automatic transmission 4x4? Does Dex/merc work or just Dexron atf, any opinions, thanks

Run Dexron III.

Cheap Aftermarket Dexron III "type" fluids are labeled DEX/MERC, And are NOT approved by any OEM. These fluids do work, BUT they are not tested to any standard, No viscosity or oxidation stability test. You have to trust a "bargain basement" fluid maker for their word.

Stay away from Dexron VI ATF, It has caused seal damage/hardening in some transmissions that were made before 2006, GM says its backward compatible, But they are not fixing any seal damage.

The ONLY Dexron III fluids to have a OEM licence are TES 295Fluids approved by Allison.
TES 295 Approved Automatic Transmission Fluids.
Castrol/Allison........................TranSynd
BP Lubricants.........................Autran Syn 295
Cognis Corporation..................Emgard 2805
International..........................Fleetrite Synthetic ATF
ExxonMobil.............................Mobil Delvac Synthetic ATF
John Deere & Company.............HD SynTran
Volvo Trucks North America.......Bulldog Synthetic ATF

Transmission fluid - FYI

Quote:

Originally Posted by storm9c1 (Post 5349960)

Is Dexron VI the new fancy synthetic stuff? Because I was told by a local shop to use the new synthetic stuff in my freshly rebuilt 4L80E (production date circa 1994, but rebuilt in 2010) on the initial fill. I already had plenty of stock of Dexron III in my garage, so I used that instead. It didn't feel right using an untried (by me) fluid in an older style trans that I just spent $$$$ to rebuild. I knew III would work, so I used it. I've also read that the synthetic stuff is great to run in any trans. Now I'm worried about what you are saying. Luckily I wasn't a guinea pig...

Dexron VI was formulated for Hydra-Matic 6-speeds....6L80E & 6L90E.
It has a special additive package to deal with "clutch to clutch shifting".
It is labeled a synthetic.....DEXRON-VI is not synthetic. It is made from a blend of Group II and Group III base oils plus the Dexron VI additives package. It does not contain any PAO (polyalphaolefin) found in group IV base oils.

A "true synthetic" uses Group IV base oils.
All TES-295 approved fluids use Group IV base oils plus a Dexron III additive package...Making them a Fully Synthetic Dexron III fluid.