Ford 2002 Explorer Owner's Manual page 263

Your vehicle was factory-filled with a 50/50 engine coolant and water
concentration. If the concentration of coolant falls below 40% or above
60%, the engine parts could become damaged or not work properly. A
50–50 mixture of coolant and water provides the following:
• Freeze protection down to -36° C (-34° F).
• Boiling protection up to 129° C (265° F).
• Protection against rust and other forms of corrosion.
• Enables calibrated gauges to work properly.
When the engine is cold, check the
level of the engine coolant in the
reservoir.
• The engine coolant should be at the "cold fill level" or within the "cold
fill range" as listed on the engine coolant reservoir (depending upon
application).
• Refer to the Scheduled Maintenance Guide for service interval
schedules.
• Be sure to read and understand Precautions when servicing your
vehicle in this chapter.
If the engine coolant has not been checked at the recommended interval,
the engine coolant reservoir may become low or empty. If the reservoir is
low or empty, add engine coolant to the reservoir. Refer to Adding
engine coolant in this chapter.
Note: Automotive fluids are not interchangeable; do not use engine
coolant, antifreeze or windshield washer fluid outside of its specified
function and vehicle location.
Maintenance and care
263