Ford 1999 Windstar Owner's Manual page 199

Maintenance and care
Do not use alcohol or methanol antifreeze or any engine coolants mixed
with alcohol or methanol antifreeze. Do not use supplemental coolant
additives in your vehicle. These additives may harm your engine cooling
system. The use of an improper coolant may void your warranty of your
vehicle's engine cooling system.
Recycled engine coolant
Ford Motor Company recommends that Ford and Lincoln-Mercury
dealers use recycled engine coolant produced by Ford-approved
processes.
For vehicles with green coolant, not all coolant recycling processes
produce coolant which meets Ford specification ESE-M97B44–A, and use
of such coolant may harm engine and cooling system components.
For vehicles with orange coolant, no recycling process has been
approved at this time and use of such coolant may harm engine and
cooling system components.
Always dispose of used automotive fluids in a responsible manner.
Follow your community's regulations and standards for recycling and
disposing of automotive fluids.
Coolant refill capacity
To find out how much fluid your vehicle's cooling system can hold, refer
to Refill capacities in the Capacities and specifications chapter.
Have your dealer check the engine cooling system for leaks if you have
to add more than 1.0 liter (1.0 quart) of engine coolant per month.
Severe winter climate
If you drive in extremely cold climates (less than –36°C [–34°F]), it may
be necessary to increase the coolant concentration above 50%. Refer to
the chart on the coolant container to ensure the coolant concentration in
your vehicle is such that the coolant will not freeze at the temperature
level in which you drive during winter months. Never increase the engine
coolant concentration above 60%. Leave a 50/50 mixture of engine
coolant and water in your vehicle year-round in non-extreme climates.
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