2004 Dodge Caravan Owner's Manual - Page 320

320 MAINTAINING YOUR VEHICLE Adding Coolant When adding coolant, or refilling the system, a minimum of 50% solution of ethylene glycol antifreeze coolant in water should be used. Higher concentrations (not to exceed 70%) are required if temperatures below 37°F ( 38°C) are anticipated. Use only high purity water such as distilled or deionized water when mixing the water/antifreeze solution. The use of lower quality water will reduce the amount of corrosion protection in the engine cooling system. Please note that it is the owner's responsibility to maintain the proper level of protection against freezing according to the temperatures occurring in the area where the vehicle is operated. NOTE: Mixing coolant types will decrease the life of the engine coolant and will require more frequent coolant changes. Coolant Pressure Cap The coolant pressure cap must be fully tightened to prevent loss of coolant, and to insure that coolant will return to the radiator from the coolant recovery bottle. The coolant pressure cap should be inspected and cleaned if there is any accumulation of foreign material on the sealing surfaces. WARNING! The warning words "DO NOT OPEN HOT" on the coolant pressure cap are a safety precaution. Never add coolant to the radiator when the engine is overheated. Do not loosen or remove the coolant pressure cap to cool an overheated engine. Heat causes pressure to build up in the cooling system. To prevent scalding or injury, do not remove the coolant pressure cap while the system is hot or under pressure.