The automatic Transmission Fluid in a 2004 Ford Mustang should be changed every 30,000 miles or once a year. The manufacturer has made this recommendation available in the owner's manual as well.
The recommended automatic transmission fluid for the 2005-2007 Mustang is Mercon V automatic transmission fluid
Type F Automatic Transmission Fluid.
Motorcraft MERCON - V - automatic transmission fluid ( I believe it is stamped into the automatic transmission dipstick )
Motorcraft MERCON - V - automatic transmission fluid in the automatic transmission Motorcraft MERCON automatic transmission fluid in the manual transmission ( according to the owners manual )
For the manual transmission ( Motorcraft MERCON automatic transmission fluid ) For the automatic transmission ( Motorcraft MERCON - V - automatic transmission fluid According to the Owner Guide
According to the 2002 Ford Mustang Owner Guide : 3.8 liter manual transmission fluid ( Motorcraft MERCON automatic transmission fluid ) 4.6 liter manual transmission fluid ( Motorcraft synthetic MERCON automatic transmission fluid )
On a 2005 Ford Mustang GT the automatic transmission does not have an automatic transmission fluid level dipstick ( and the manual transmission fluid level is checked underneath the vehicle at the transmission fill plug )
The automatic transmission fluid dipstick is just to the passenger side of the engine by the firewall
Motorcraft MERCON-V automatic transmission fluid ( it will show the type used either on the automatic transmission dipstick handle or engraved into the dipstick )
Motorcraft MERCON automatic transmission fluid in the manual transmissions on a 2004 Ford Mustang ( according to the Owner Guide )
Motorcraft MERCON automatic transmission fluid for your manual transmission
Type F