Radiator Care

Looking After Your Radiator


It is imperative that the correct coolant is used and that it is well maintained to ensure long life from your radiator. Coolants must not be mixed and must be replaced when stipulated by the manufacturer - it may look the same after this date, but may no longer be doing its job.

Aluminium is normally seen as corrosion resistant because an oxide layer forms on the exposed surfaces that acts as a barrier to further corrosion. However, in conditions where this barrier is broken, corrosion can be very rapid as aluminium is actually a very reactive metal. This is why care of the coolant becomes even more important when using an Aluminium radiator.

Copper/brass cores are quite tolerant to water quality and although there are some chemicals that can cause problems, and corrosion inhibitors must be used, normal tap water is reasonably well tolerated. The same does not apply to aluminium cores.




Use the correct coolant specified for the vehicle. Coolants are selected to suit the vehicle. The requirements for aluminium and copper brass radiators are different and a common coolant may not suit. The radiator is not the only part of the coolant system and some coolants may have been selected to protect other parts of the cooling system.

Use the correct concentration of coolant. Coolants for aluminium radiators are mainly composed of ethylene glycol but also contain chemicals to protect the cooling system. High-ethylene glycol content will actually reduce the heat rejection performance of the cooling system*. This results in the engine running hotter than normal when the thermostat is fully open.

  1. Always use good quality water to blend with the coolant. Distilled water, demineralised water or rain water are the preferred options. Many town water supplies contain high concentrations of chemicals, such as salts, that are very damaging to an aluminium radiator.
  2. Do not mix coolants. Many coolants use different chemical systems and combining them may neutralise the effect of the chemical protection.
  3. Replace the coolant at the specified intervals. During service the ethylene glycol eventually deteriorates and becomes acidic. This acid will attack the internal oxide coating on the aluminium and lead to corrosion.
  4. Flush the coolant system with clean water after the coolant is drained. It is important to remove any scale or deposits from the system and remove old coolant and chemicals that may adversely affect the new coolant. The heater core is part of the cooling system and must also be flushed of coolant.
  5. Check that the system is properly filled and that any air is removed. Air in the coolant will increase the rate of corrosion and air pockets can lead to uneven cooling of the engine. Some vehicles have trapped air pockets and it may be necessary to bleed air from vent positions to allow the air to escape. The vehicle should be run for a while before the cap is replaced to allow the air to escape.
  6. If the coolant is topped up it should be with a properly mixed coolant solution so that the concentration of the system is not changed. Ensure that the coolant type is the same as is already used in the vehicle to ensure it is compatible.

*Low-ethylene glycol content will not carry the required concentration of additives and can also result in an incorrect Ph level. This leads to damage of the radiator due to corrosion. NOTE: Ethylene glycol is toxic. Please follow specific manufacturer instructions for handling and disposal. It is also important to clean up spills.


What to do if your car overheats?


If your radiator overheats, pull over and raise bonnet to assist cooling. Do not remove radiator cap or add cold liquid. Allow time for the radiator to cool down, liquid should only be added to the radiator when it is cool. Apart from the danger of being burnt by the radiator, removing the cap when hot will cause hot liquid and steam to surge upwards as the pressure in the system is released. Adding cold liquid to a hot radiator can also crack the engine block. If you must add liquid while it is still a little warm have the engine running to mix the cooler liquid as it is added and add slowly.