Opinions on Transmission Fluid Changes

[foamypirate]

Originally Posted by hatzie

For a TH700R4 in good condition fill with Dexron VI.
There is no such thing as Dexron III anymore. It's been gone since 2006 when GM stopped buying and licensing it.

Here's GM Tech Service Bulletin 04-07-30-037D on the "new" Dexron VI transmission fluid. Our trucks fall into the "2008 and Prior GM Passenger Cars and Light Duty Trucks" category...
It's worth reading the recommendation to not use Dexron VI in Power Steering, Manual Transmissions, and Transfer cases that originally called for Dexron III.

"The content of this bulletin does not apply to manual transmissions or transfer cases. Any
vehicle that previously required DEXRON®-III for a manual transmission or transfer case
should now use P/N 88861800. This fluid is labeled Manual Transmission and Transfer Case
Fluid. Power Steering Systems should now use P/N 9985010 labeled Power Steering Fluid."

Dexron VI is expensive, and in my opinion, a complete waste to run in a 700R4 or an TH350/TH400.

Something that says it's suitable to use in a transmission that called for Dexron III originally will be perfectly fine and acceptable, even Wal-Mart Supertech. Heck, even a lot of the big name trans guys have no qualms with Supertech. There is no need to spend the big bucks on Dexron VI unless you are running a late model trans, in my book. You can get a gallon of Dexron III compatible Supertech for $15 or so. I've been running it in my GM autos for years without a single problem.