Free Diagnostic Tool

Here is a quick little trick that works on my 2001 Cobra and may work on your mustang.

1) Put key in ignition & turn to 1st position

2) Press and Hold the trip button in

3) Turn key to 2nd position
(Hint: the radio comes on in 3rd position)

After a few seconds your odometer will
display "test" and all the dash gauges will
cycle from min to max and back to min.

4) You can now release the trip button

Now in test mode, every time you press the trip button the odometer will display another real time function. 

I don't know all of the functions but some of the my favorites are:
Illuminate all dash warning lights;
display digital tach;
fluid pressures;
engine temp.

All displays are in real time and you can start your car while in test mode.

I use this feature to monitor engine temperature (in degrees C) while driving on the track.  The display gives one degree increments instead of the factory Low/High gauge.

Note, once the key is removed, the car will go back to normal. 

        94-03 Fluid Capacities

Engine Oil
    3.8L V6                            5 qts
    5.0L V8                            5 qts
    4.6L V8 SOHC                    5 qts
    4.6L V8 DOHC                    6 qts

Fuel Tank                             15.4 gal

Cooling System
    V6 Models                        11.8 qts
    V8 Models                        14.1 qts

Automatic Transmission
    AODE                              12.5 qts   
    4R70W 3.8L V6                 13.9 qts
    4R70W 4.6L V8                 12.8 qts

Manual Transmission
    T5                                  5.6 pts
    T45                                 6.6 pts

Rear Differential
    7.5 Inch Ring Gear             3.25 pts
    8.8 Inch Ring Gear             3.75 pts

                Fluid Types

Engine Oil
API Grade SG or SG/CC Multigrade
5W-20, 5W-30 or 10W-30 (per climate)

Fuel
    All Except Cobra    87 Octane or higher
    Cobra                  91 Octane or higher

Engine Coolant
50/50 Ethylene Glycol Antifreeze & Water

Brake Fluid
DOT 3 Heavy Duty Brake Fluid

Power Steering Fluid
Mercon ATF

Automatic Transmission Fluid
    1998 and earlier    Mercon ATF
    1999 and later      Mercon V ATF

Manual Transmission Fluid
Mercon ATF

Chassis Grease
SAE NLGI No.2 Chassis Grease

Differential Lubricant
80W-90 GL-5 Gear Oil (Mustang & GT)
75W-140 w/Friction Modifier (Cobra)