Ford F-150 2010 Owner's Manual page 376

Maintenance and Specifications
Severe climates
If you drive in extremely cold climates (less than –34°F [–36°C]):
• It may be necessary to increase the coolant concentration
above 50%.
• NEVER increase the coolant concentration above 60%.
• A coolant concentration of 60% will provide freeze point
protection down to -62°F [-52°C]. Increased engine coolant
concentrations above 60% will decrease the overheat
protection characteristics of the engine coolant and may cause
engine damage.
• If available, refer to the chart on the coolant container to
ensure the coolant concentration in your vehicle will provide
adequate freeze protection at the temperatures in which you
drive in the winter months.
If you drive in extremely hot climates:
• It is still necessary to maintain the coolant concentration
above 40%.
• NEVER decrease the coolant concentration below 40%.
• A coolant concentration of 40% will provide freeze point
protection down to -12°F [-24°C]. Decreased engine coolant
concentrations below 40% will decrease the corrosion/freeze
protection characteristics of the engine coolant and may cause
engine damage.
• If available, refer to the chart on the coolant container to
ensure the coolant concentration in your vehicle will provide
adequate protection at the temperatures in which you drive.
Vehicles driven year-round in non-extreme climates should use a 50/50
mixture of engine coolant and distilled water for optimum cooling system
and engine protection.
What you should know about fail-safe cooling (if equipped)
If the engine coolant supply is depleted, this feature allows the vehicle to
be driven temporarily before incremental component damage is incurred.
The "fail-safe" distance depends on ambient temperatures, vehicle load
and terrain.
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