How to change car coolant / radiator flush

In this tutorial i will show you how to change your car’s coolant fluid and also how to flush the radiator. these steps where done on my 2008 automatic Mazda 2.

What you will need:

  • Coolant fluid recommended by your car manufacturer
  • Access to garden hose or water
Coolant fluid

Coolant fluid

What to do:

1. Empty the old coolant fluid:

  • Make sure your engine is cold, at least 1 hour since you drove your car
  • Open the radiator drain plug and let the old coolant drain for at least 10 min.
Radiator bottom drain plug

Radiator bottom drain plug

  • Open the radiator top plug to let coolant fluid drain faster
Radiator top plug open

Radiator top plug open

Note: make sure to dispose of the old coolant properly, this is toxic waste. take it to a garage and ask them to dispose of it

  • Remove the reservoir tank and dispose of the coolant fluid inside
Reservoir tank

Reservoir tank

Old coolant disposal

Old coolant disposal


2. Flush the radiator:

  • Open the top lid of the radiator, attach a garden hose to the opening and watch the water drain from the bottom drain plug. this will flush only the radiator, not the all cooling system. if you want to flush the all cooling system, continue reading
  • Close the radiator bottom drain plug
  • fill the radiator with distilled water or tap water
  • Close the top radiator lid
  • Start your car engine
  • Put the air conditioning on full heat. this will open the heater core thermostat and will allow the water to go to the heater, thus replacing old coolant fluid. this is more relevant to older car models
  • Watch closely on your engine temperature in your console, any high temperature indication, turn off the engine
  • Look at your engine and wait for the radiator fan to start working. when this happens, it means the the 2nd thermostat is now open, allowing hot coolant to flow from the engine to the radiator, thus replacing old coolant fluid
  • Wait couple of minutes and turn off your engine
  • Wait an hour
  • Open the radiator drain plug and let the old coolant drain for at least 10 min.
  • Close the radiator bottom drain plug


3. Refill with new coolant:

  • Open the radiator top plug and pour new coolant inside


To make sure there are no air bubbles, pour the new coolant very slow, around 1 liter per min. this will keep trapped air to a minimum

  • Fill also the reservoir tank between the marks of MIN. & MAX
Filling new coolant

Filling new coolant


4. Watch coolant level:

  • Start your car and watch the temperature gauge, for any sign of high temperature or any coolant leak immediately stop your engine
  • Turn the heat on maximum to open the heater thermostat
  • Wait until the radiator fan start to work. after a few min. turn of your engine
  • Wait 1 hour
  • Open your radiator top plug and if missing, add coolant
  • Check your reservoir tank, if coolant is missing, fill between the MIN & MAX marks
  • In the next few days watch closely for any leak or indication of high engine temperature. watch closely also for low level coolant and add if needed



i am not a mechanic nor intend to be. i did these steps on my car after learning the procedure, i am not responsible in any way if you make a mistake. there are lots of car manufacturers out there and each car is different. different cars require different method.

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Posted in Cars
4 comments on “How to change car coolant / radiator flush
  1. John says:

    How much litters of coolant aoorox goes in the Mazda 2 2008?
    Also, what is your tyre size?
    Just wondering if a 185/65/R 14 will fi on.

  2. If someone considers antifreeze then it is very important to know in what proportion coolant mix with water to form a perfect antifreeze. An antifreeze not only transfers heat from the engine but also it prevents rust and corrosion in the interior part of our car. Similarly a flush helps in removing the deposits which get pushed out with the old antifreeze. Because these build ups can cause overheating and also can damage radiator. Here, you blog has been provided with the way to change car coolant radiator flush which is quite appreciating. Thus, I would like to say thank you for sharing this.

  3. Adi Sharaby says:

    Thanks John for the kind words.
    also, in a Radiator that wasn’t treated properly (i.e. filled with tap water etc..) when doing a flush with aggressive chemicals, leftovers like dirt and rust that till now were attached to the radiator, can detach and clog the cooling system.

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