Ford 2003 Mustang Workshop Manual page 1842

The 3.8L cooling system components include the:
block heater
engine coolant temperature (ECT) sensor
fan blade, fan motor and fan shroud assembly
radiator
radiator cap
radiator draincock
coolant pump
coolant thermostat
oil filter adapter
radiator overflow hose
coolant expansion tank
upper radiator hose
lower radiator hose
The fan blade draws air through the radiator to help cool the engine coolant.
The fan motor:
operates only when the ignition switch is in the RUN position.
will not operate with the switch in the OFF position.
The engine coolant:
flows through the radiator tubes and is cooled by passing air over the cooling fins.
is then circulated from the radiator outlet tank through the coolant pump and into the cylinder
block to complete the circuit.
A closed coolant thermostat returns the engine coolant to the coolant pump. An open coolant
thermostat allows the engine coolant to flow to the radiator.
CAUTION: Engine coolant provides freeze protection, boil protection, cooling efficiency,
and corrosion protection to the engine and cooling components. In order to obtain these
protections, the engine coolant must be maintained at the correct concentration and fluid level
in the degas bottle (4.6L) or coolant expansion tank (3.8L).
When adding engine coolant, use a 50/50 mixture of engine coolant and deionized water.
To maintain the integrity of the coolant and the cooling system:
NOTE: The addition of Motorcraft Cooling System Stop Leak Pellets, VC-6, darkens Motorcraft
Premium Gold Engine Coolant from yellow to golden tan.
Add Motorcraft Premium Gold Engine Coolant VC-7-A (in Oregon VC-7-B) or equivalent
meeting Ford specification WSS-M97B51-A1 (yellow color). Use the same coolant that is
present in the cooling system. Do not mix coolant types.
Do not add/mix orange-colored Motorcraft Speciality Orange Engine Coolant VC-2 or equivalent