Types: Dexron is a formulation for a particular type of lubricant (transmission fluid). Type F, Type T, ATF and Mercon are other formulations. They are chosen by the manufacturer based on the mechanical system in question and what the lubricant must be able to withstand and continue to perform. Apparently, at least one newer fomula meets two older formula specs: you can find Dexron/Mercon fluid.
Numbers: However, as the specification becomes more stringent or higher in grade, the numbers change. We are now up to Dexron IIIE. Do NOT substitute a lower number Dexron or Dexron/Mercon formula, when a higher one is called for. Don't stick Dexron/Mercon rated as equivalent to Dexron II in a gearcase calling for Dexron IIIE. Your lubricant may not be able to take it, break down, and cause you mechanical problems. You CAN use Dexron III in place of Dexron II, though...
Manufacturers: If you go to the right shop, you can find a manufacturer (say, Quaker State or Mobil) that makes some or all of these types of fluids: Dexron, Type F, Type T, DOT 3, ATF, SAE 30, 5W-50 and 10W-30.
From the accuratetrans web site:
"Ford, GM, and Chrysler each have different specifications for fluid formulations. Generally the differences between fluids is mostly in the type and amount of friction modifiers used in each formula.
General Motors Dexron« III is the most current specification. Formulated for higher oxidation resistance and friction stability, Dexron« III supersedes Dexron« II and Dexron« and can be used in any GM transmission."
Finally, keep in mind that these fluids can serve more than one purpose. My Montero uses Dexron in my power steering system, and it uses DOT 3 (usually a brake fluid) for both brakes and clutch. I once destroyed the lines in a brake system by putting transmission fluid in the master cylinder (it was dark, and it was too late, when I realized what happened). THAT is why it is important to put the right fluid in. <img src="/forums/images/graemlins/kewl.gif" alt="" />
