According to the 2003 Ford Mustang Owner Guide :
4.6 liter manual transmission ( MERCON automatic transmission fluid )
75W-90
about 4 quarts, look at manual for specific measurements
is it auto or manuel?
The fluid used in the hydraulic system for the convertible top of a 1966 Ford Mustang is typically a hydraulic fluid, often referred to as "convertible top fluid" or "hydraulic top fluid." It's important to use a fluid that is compatible with the system, commonly either automatic transmission fluid (ATF) or a specific hydraulic fluid recommended by the manufacturer. Always check the owner's manual or service documentation for the precise specifications.
ifits a manual its gear oil u add and there should be a plug on tranny to check and add oil if its a auto it goes through dipstick
DOT 3
According to the 2002 Ford Mustang Owner Guide : The 4.6 liter V8 manual transmission takes ( 8.0 pints which would be 4.0 quarts ) ( of Motorcraft SYNTHETIC MERCON automatic transmission fluid , meeting Ford specification ESR-M2C163-A2 ) * to the bottom of the transmission fill hole , on a level surface
The owners manual shows Motorcraft Full Synthetic Manual Transmission Fluid for the 5 speed manual transaxle
you dont use tranny fluid in a manual trans you lube it
On an automatic, the fluid goes down the dipstick tube. On a manual, the fluid goes in the check hole on the side of the transmission.
ATF+4, automatic transmission fluid
Motorcraft Mercon Automatic transmission fluid according to the manual ( For the automatic and the manual transaxle / transmission )