Transmission fluid is vital to the proper operation of a transmission. This fluid not only lubricates the moving parts of the transmission, it also acts as a coolant, protecting the transmission against fatal heat. Transmission fluid for Mustangs should be checked at least every six months or 6,000 miles.
Park the vehicle on a level surface. Apply the parking brake.
Run the engine until it reaches normal operating temperature.
Shift the gear selector lever through all of the gears while maintaining pressure on the brake pedal.
Place the transmission in the "Park" position.
Wipe away all dirt and debris from the top of the transmission dipstick, using a clean rag. Pull the transmission dipstick from its tube. On a Mustang, the transmission dipstick is located on the passenger side of the engine, between the engine and the transmission. The top of the dipstick will be curled into a circle.
Locate the transmission fluid level marks towards the tip of the dipstick. The fluid level should be above the "add" mark and just below the "full" mark.
If required, add Ford automatic transmission fluid (Ford specification #ESW-M2C33-F / Type F) by pouring new fluid into the dipstick tube. Take care not to overfill the transmission.
