Ford 2003 Mustang Workshop Manual page 1862

4. Install the coolant hose connection without the thermostat.
5. NOTE: Refer to the cooling system flusher manufacturer's operating instructions for specific
vehicle hook-up.
NOTE: The addition of Motorcraft Cooling System Stop Leak Pellets, VC-6, darkens Motorcraft
Premium Gold Engine Coolant from yellow to golden tan.
Using an appropriate cooling system flusher, flush the engine and radiator.
Use Ford Premium Cooling System Flush VC-1 or equivalent meeting Ford specification ESR-
M14P7-A. Always flush the cooling system with water thoroughly after using the VC-1 flush and
prior to filling the cooling system with the same coolant that was present in the system. Do not
mix coolant types.
6. Install the thermostat.
7. Backflush the heater core. For additional information, refer to
section.
8. Fill the cooling system. For additional information, refer to
Bleeding in this section.
Heater Core Backflushing
Cooling System Draining, Filling and
in this