How to change your Coolant.

by Andrew Automoto2. January 2014 09:26

When changing your Engine coolant it is important you use the right type of coolant. There are 3 different types of coolant Orange/red, Yellow and green. All three types of Coolant come with a Ethylene glycol  and water base, however it is the chemicals added that separate the three different coloured Coolant.

The green is the most commonly used and for a long time was the only type of coolant on the market. Green coolant usually contains a number of inorganic corrosion inhibitors that have immediate corrosion protection, because they maintain the pH solution. The Green Coolant are consumed or transformed chemically as they work.

  • Found in all service stations and department stores.
  • Castrol
  • Nulon

Red coolant or Dexcool-type coolant use organic acid technology to inhibit corrosion, and are referred to as OAT based coolants. OAT coolant are said to last longer than your green coolant, because the added chemicals  added are not transformed as they work but rather work straight away inhibiting corrosion. The chemicals used in OAT’s protect metal from corrosion by forming a thin coating on them. Because of this they are not as fast acting as conventional inorganic formulas. As long as you keep the cooling system full and coolant is not leaking or diluted with water or green or yellow antifreeze, OAT coolant will continue to function properly

  • Toyota Red
  • Dexcool
  • Subaru

Yellow is the third type of coolant and is a hybrid coolant known as HOAT. One of the main problems with OAT is that they are not compatible with conventional coolants, The chemicals used in OAT coolant react with some of the inorganic salts and other components of Conventional Coolant causing a red gel, or cloudiness. Hoat coolant is a Hybrid and because the added chemicals contain both ingredients form OAT and Green Coolant it is usually compatible with all colours of Coolant.

  • Calibre
  • Tecatoly
  • Nulon

When changing your Engine coolant make sure you have had your engine off for at least two hours, giving time for it to cool down. Hot Coolant will scald you.

1.       Remove the radiator cap and open the radiator drain cock. And let the coolant drain into a pan.

2.       Move the heater on your dashboard to hot, so you will open your coolant control valve.

3.       If there is a cap on your reservoir (pressure cap) remove it and open the drain cock. If there is no drain cock, remove the lower radiator hose from the radiator.  This will remove 40-45% of the coolant.

4.       Recap all or replug anything you have unhooked or opened, and fill the radiator with water.

5.       Start the vehicle and let it run with your heater on high for 10minutes.

6.       Turn the engine off and let it cool….Drain the engine again.

7.       Repeat steps 4-6.

8.       All systems take a mixture of 50% water and 50% coolant. At this point it is best to check your owner’s manual to find out how much your vehicle holds.

9.       Fill your car with 50% coolant, and then 50% water

10.    Start your car up again and let it run with the heater on high for 10 minutes, this will release any air pockets

11.    Top up with coolant and water

12.    Turn the dashboard temperature control back to cold and you’re ready to go.

Coolant is highly toxic, and usually has a sweet smell and taste, that attracts animals and children to it. It is recommended you keep you coolant in an air tight container up high, until you can dispose of the liquid properly.


For more information on Coolant and how to dispose of it see - Coolant

If you do not understand any of the instructions or do not have an understanding of Automobiles it is recommended you see an authorised mechanic to perform all vehicle maintenance. See for your local authorised mechanic or dealership.


 ‘The information provided in this article is for general advise only.  It is not intended for instructional use.  Use of the information is at your own risk.  We recommend you seek the advice of a trained professional.'