If I have a Ford AOD Transmission that may be filled with Mercon ATF (i really don't know, the carfax of the vehicle said that it was done at 15k miles and it has 46k now, but it was done in 2001). I know that Mercon was discontinued and a TSB by Ford was put out saying for most applications to use Mercon V instead. My question is that if I just do a drain-and-fill w/filter and gasket replacement and the system is filled with Mercon with Mercon V, it will be about a 50-50 mix of the two until the next change. Is it a bad idea to have the 2 different standards of fluid in the Transmission at the same time? Or are they compatible? Would I experience better lubrication if I take it to a shop with a fluid exchange machine for the first time and then just do the 30k-mile drain-and-fill procedure myself from then on? Also, is there any significant chemical/performance differences that you are aware of between the Motorcraft Mercon V ATF and SuperTech Mercon V ATF? If the Motorcraft would not provide very much of an advantage, then the SuperTech would be much less expensive, or is it a "you get what you pay for" scenario?

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the 5 is backwards compatible, hurts nothing. But I would use the motorcraft