During the past 5 years various Toyota automatic transmissions have come from the factory filled with Dexron III fluid, Toyota Type T-IV fluid or Toyota WS fluid. The Toyota owners manuals and technical service bulletins advised owners not to mix these fluids or substitute one for the other.
Now Walmart has come out with a Supertech Dexron VI fluid for about $3.30 a quart which it claims is "suitable for Dexron II, Dexron III, Toyota Type T-IV and Toyota WS applications."
http://i5.photobucket.com/albums/y18.../supertech.jpg
So owners are going to be confused and wondering if it's safe or risky to use Walmart's fluid and wondering if it's use might invalidate Toyota's 5 year / 60,000 mile powertrain warranty.