How to Change Antifreeze Coolant

Automobile cooling system.

The antifreeze in your car's cooling system contains ethylene glycol to keep the coolant mixture in a liquid state at very low temperatures and additives that prevent corrosion and lubricate the water pump. When the thermostat between the radiator and the engine is open, the antifreeze circulates through channels in the engine block and back into the radiator. The fan and radiator remove the heat from the antifreeze. Over time, extremes in temperature break the additives down and the antifreeze needs replacing. Periodically draining and replacing the coolant keeps your engine running at the right temperature and prevents damage from rust and calcium deposits.

Things You'll Need

• Catch pan Antifreeze

Instructions

1. Consult your owner's manual to determine the capacity of your cooling system. Buy enough antifreeze to fill the system 50 to 70 percent full.

2. Start with a cool engine. Remove the radiator cap by unscrewing it counterclockwise.

3. 

   Put a drain pan beneath the radiator petcock or drain plug. Open the plug and let the radiator drain completely.

4. Close the petcock or drain plug and refill the radiator with water. Leave the radiator cap off.

5. Run the engine with the heater on until the water is circulating through the engine block and back into the radiator.

6. Drain the radiator again. Close the petcock and add antifreeze sufficient to make a 50 to 70 percent solution.

7. Run the engine again with the heater on so the coolant circulates. Let it cool, then top off the radiator and the coolant reservoir with antifreeze. Reinstall the radiator cap.

Tips & Warnings

• Be sure to buy the right kind of antifreeze for your vehicle. Decrease rust and lime deposits by using only distilled or demineralized water in your cooling system.

• Animals love the taste of antifreeze, yet even a small amount is toxic to them. Collect it in a drain pan and dispose of it properly. Never remove the radiator cap when the engine is hot.

Resources

• Auto Upkeep's guide to cooling systems
• Advice on cooling systems from Car Talk