I have a 97 F150 with the 4R70W transmission.I had dropped the transmission pan last October and changed the filter and just the fluid in the pan.The reason I did this was because of the vibration when going in to overdrive.Well it corrected it but it came back so I decided to have the transmission flushed. I took it to a Valvoline Instant oil change center and they would not refill with Mercon 5, they said they can only refill with what the vehicle originally came with.So I got the Dexron/MerconIII.Trans now works fine.I know some of you have switched to Mercon V,are you sure you can do that without damaging the transmission?

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Dennis

 

Ford recommends Mercon V for the 4R70W. The 1997 did come with Mercon as the fatory fill, but in 1998 Ford changed the recommendation to Mercon V.

Mercon won't hurt it, but Mercon V would have been better in this case.

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