1997 Ford Aerostar Owner's Manual - Page 240

Adding Engine Coolant Adding engine coolant to reservoir RWARNING Do not put engine coolant in the container for the windshield washer fluid. When the engine is cool, add a 50/50 mixture of engine coolant and water to the engine coolant recovery reservoir - DO NOT ADD DIRECTLY TO THE RADIATOR. Add straight water only in an emergency, but you should replace it with a 50/50 mixture of coolant and distilled water as soon as possible. Check the coolant level in the coolant recovery reservoir the next few times you drive the vehicle. If necessary, add enough of a 50/50 mixture of coolant and water to bring the liquid level to the fill line on the reservoir. RWARNING Never remove the coolant recovery cap while the engine is running or hot. If you must remove the coolant recovery cap, follow these steps to avoid personal injury caused by escaping steam or engine coolant: 241