Changing auto transmission oil on 72?

[storm9c1]

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...

[clinebarger]

Originally Posted by storm9c1

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.