I know that after reading several articles and reading my owners manual that the AW71 transmission in my 91' 740 calls for Dex/Merc II...

That being said, there have been many improvements in and upgrades in ATFs over the last 20 years. One thing I know being a Ford guy, is that after Ford came out with Merc-V they immediately began recommending it be used in their older vehicles (all that called for MercIII, II) and owners reaped the benefits of their transmissions working better in general, and soon after Ford superseded all prior MercII, and III products with Merc-V. GM, and most other automakers did the same thing, changing from full petroleum ATFs to full or semi-synthetic high-friction modified ATF's that stay cleaner, break down less, and perform/operate exponentially better.

OK, so now for the 64,000$ question: having access to several different types of ATF, AND multi-vehicle ATFs, which I think are a sham unless they are a reputable synthetic manufacturer, AND having about a case of full synthetic Merc-V, I should be able to use Mercon-V as a suitable replacement for dex/mercII. I know dex-VI is a lot thinner than dexII or dexIII, but Merc-V is roughly the same weight as Dex/Merc.

Any ideas? I'm going to change my trans fluid soon and I'm probably going to use the merc-V.

 

Actually I have no idea whether it's an AW71or an AW70...

 

Use the newest version of Dexron. That's all you can get anyway.
You can't buy SD/SE motor oil any more either.
The Mercon should suffice.
Ed

 

e4od could care less about Mercon V. They self-destruct at 200k miles like clockwork.

If your car is turbo, I would think you have the AW71, although not 100% sure.

For some reason, using a Mercon fluid does not seem right to me. Since you are a Ford guy, I would save that for Fords, and get Dex/Mercon ATF in there, especially since your transm might not be a young lad anymore.

 

Oh, you don’t have to tell me about E4ODs... i've only owned one personally. A 94 F150 4x4 with like 80k miles on it... o/d shift solenoids went out about 3k after I bought it. I just was thinking about using the syn fluid I have rather than buying new fluid.