Mercon or Mercon V

[steelrain7]

I have a 4R100 transmission. The manual says use only Mercon ATF not Mercon V. I have read a few posts on here that said I can use Mercon V in my transmission. When I was at Autozone buying the filter, their computer said to use Mercon V. I informed the guy that my owner's manual said using Mercon V in the 4R100 will cause damage. Can anybody verify that I can or cannot use Mercon V in my 4R100? I want to change all of the fluid tomorrow. Thanks.

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[tomlin]

Use Mercon only in the 4R100. The 4R70W takes the Mercon V. I believe the Mercon V has a different friction modifier package in the fluid composition.

[Mark Kovalsky]

MERCON has been discontinued. Ford changed MERCON V a few years ago to make it compatible with transmissions that used MERCON.

Autozone was right. MERCON V is now the right fluid for your 4R100.

[glc]

Do a complete change, including draining the torque converter, and put name brand Mercon V in.

[Patman03SprCrw]

^^ agreed GLC is on the money

[Kattumaram]

Mercon V compatibility covers those applications where Dexron I, II and III, Mercon and Chrysler 3 and 4 are recommended. For my money and transmissions I'll use Chrysler ATF+4. ATF+4 is completely compatible with Ford transmissions and will outlast Mercon V by a factor of two. In addition, shift firmness and quality are improved and torque converter clutch shudder is eliminated.

[glc]

I would NOT recommend you use ATF+4 unless the label specifically says it meets Mercon V specs. Some manufacturers, such as Amsoil, have a full synthetic "universal" fluid that meets both specs.