What is the proper type of fluid for the 700r4 between Dexmerc III and Dexmerc VI? Autozone told me that Dexmerc VI is the proper fluid, not that I trust Autozone guys too much. But after reading some posts on diesel and other forums, a lot of people are running Dexmerc III. So what is the proper fluid to be using in the 700r4? Since Dexmerc VI is a synthetic, it kinda makes sense in my mind since the thinner synthetic fluid would reach the overdrive clutch packs better than regular transmission fluid.