Dexron III VS. Dexron VI (ATF & PS Fluid)

I'd like to pick your guy's brains here on this one. Is Dexron VI backwards compatible with Dexron III? I know GM says yes (but not for Power steering applications). After spending a few hours of doing research, I can't find a solid answer on this one. Even though GM, (Manufacturer of Dexron fluids) says it is backwards compatible, others have reported issues with using Dexron VI in a transmission that requires Dexron III.
The license for Dexron III expired in 2006, and therefore, technically NO ONE is making a true Dexron III fluid anymore, only fluids that are compatible with the original Dexron III. Thats fine, and I'm ok with using something like Valvoline's Dex/Merc ATF (Blue bottle), but Valvoline also makes a "Maxlife" Dex/Merc (Red Bottle).

Somebody PLEASE correct me if I'm wrong, but I believe now that Valvoline color codes the bottles of thier Dex/MERC ATF
Blue = Dexron III
Red = Dexron VI

The red bottle Maxlife Dex/Merc is of lower viscosity when comparing the MSDS to the Blue bottle (Red bottle viscosity is 28.8 mm2/s compared to the blue bottle which is 43 mm2/s). This makes sense because its inline with the differences between the real GM manufactured/licensed Dexron III and VI fluids.

That being said, would you put a Dexron VI compatible fluid in your transmissions and Power Steering system. I've been using the red bottle Valvoline Maxlife Dex/Merc for my trucks power steering and in my wife's 99 Camry transmission and power steering. I now believe this a mistake. I'm thinking a PS flush and a few tranny drain/fills are in order. What do you think?

 

I know in the gm duramax trucks with the Allison trans on trucks made before '06 there have been many problems associated with using the dex vi in the tyrannys. The seals on the older trannys that came with dex III are not compatible with dex vi and was causing them to harden. Not sure if all trannys made before dex vi would have the same problem but its somethjn to think about.

 

I flushed the Maxlife ATF (Dexron VI) out of the power steering of my tacoma and camry and replaced with Valvoline Dex/Merc (blue bottle - Dexron III). The steering feels slightly firmer? but maybe thats just wishful thinking. Will do a single drain and fill on the camry transmission when time allows.