How to put antifreeze in radiator

Written by allen moore
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How to put antifreeze in radiator
The radiator is vital to your car's engine (radiator humour image by John Sfondilias from

A car radiator must be filled with a mixture of equal parts coolant and distilled water in order for it to properly cool the vehicle's engine and related systems. If the system has too much coolant or too much water, the boiling point is altered and the system can't function properly. Most modern vehicles no longer work with the old green antifreeze, so make sure when preparing to fill your radiator, you have the proper mixture of coolant and distilled water, as well as the proper type of coolant, recommended by your car's manufacturer.

Skill level:
Moderately Easy

Things you need

  • 2 gallons coolant
  • 2 gallons distilled water
  • Funnel (optional)

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  1. 1

    Allow the vehicle's cooling system to completely cool down. Opening a hot cooling system can result in serious burns or even death.

  2. 2

    Remove the radiator cap, or coolant overflow bottle cap, depending on your car's cooling system set-up.

  3. 3

    Place the funnel in the opening to the radiator or coolant overflow bottle and pour one gallon of coolant into the system. When done, pour in one gallon of distilled water.

  4. 4

    Pour 1/2 gallon of coolant into the coolant bottle which you emptied in Step 3. Fill the bottle the rest of the way with distilled water so you have one gallon of a 50/50 mixture of coolant and distilled water.

  5. 5

    Pour the 50/50 mixture into the radiator or coolant overflow bottle until the coolant rises to the base of the radiator neck, or the cold fill line in the overflow bottle. Reinstall the cap when done.

  6. 6

    Start the engine and allow it to run for a minute or two and then shut it back off. Open the cooling system again and top the coolant level, which will have dropped a bit as air pockets leave the system. Check the cooling system again after the next drive cycle, when the engine is once again cold.

Tips and warnings

  • Never mix green antifreeze with any other colour coolant. If your vehicle is equipped with green coolant, only use green coolant. If orange, only use orange, etc. Mixing the types of coolant can lead to a chemical reaction that creates a corrosive jellylike substance that rots the inside of your radiator and engine.

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