Do the different colours of coolant matter?

When looking for engine coolant or antifreeze, you may have seen various different colours available to buy. As a general rule, you shouldn’t mix different types of coolant. However, nowadays, with new vehicle models, the colour of the coolant you choose doesn’t always matter. Whereas on older models, using the wrong type of coolant could cause damage to the cooling system and engine.  

What are the different types of coolant?

The main different types of coolants are green, orange, red or pink. The different types of coolants depend on the chemical make-up of the cooling liquid.  

Green Coolant 

Green Coolant is made from Ethylene Glycol and is also known as Inorganic Coolant. Essentially it works by transferring heat away from the engine and out through the radiator. Generally, Green coolant is used in older vehicles and lasts 2 years or around 30,000 miles. 

The Ethylene Glycol in coolant acts as anti-freeze, as it has a lower freezing point than water. When mixed with water it has a freezing point of -40 °C, meaning in freezing temperatures, it still remains as a liquid. As well as anti-freezing properties, Ethylene Glycol has a much higher boiling point than water, of 197 °C. 

Another benefit to the green coolant is that it has various additives to help prevent corrosion and rust from building up in the engine and radiator. This helps to protect your engine from the corrosive effects of Ethylene Glycol.  

Orange Coolant 

Orange Coolants are also known as OAT coolants. OAT coolant stands for Organic Acid Technologies and is specifically designed for newer vehicles that contain more nylon or aluminium parts in them.  

Similarly, to green coolant, orange coolant works by absorbing the heat from the engine and releasing it out through the radiator.  

While Green Engine Coolant contains Ethylene Glycol, the chemicals that give orange coolant its cooling properties consist of organic acids and silicates. The exact composition of orange coolant will vary depending on the manufacturer.  

These silicates and acids in orange coolant form a protective layer on the aluminium and other metals present inside the engine to lower the corrosive effect of the chemicals present in the coolant.  

Orange coolant can also be referred to as an Extended Life coolant. This is because it generally lasts longer than inorganic Coolants. OAT coolants tend to last around five years or 150,000 miles.   

Red/Pink Coolant 

Red or pink coolant is another type of OAT coolant that is commonly used in newer vehicles. It works in the same way as orange coolant in removing excess heat from the engine and protecting the engine from freezing temperatures.   

One of the factors that distinguish the difference between Orange and Red or Pink coolants, is that Red and Pink coolants do not contain silicates or Phosphates. This is because silicates or phosphates can be damaging to some types of seals, gaskets and metals in certain models of vehicles.  

Red or pink OAT coolant typically lasts for the same amount of time as Orange Coolant (about five years).    

Can you mix different coolant colours? 

The reason why mixing coolant is not usually recommended is because the different chemicals can react with each other and can cause damage to the engine.  

Some modern types of coolant are known as universal coolants. These coolants can be mixed without causing any harm to the engine or cooling system.  

If you do mix coolant, and the two types of coolant you mix are not compatible, it could create sludge that can block the system, it can also increase corrosion in your engine and cooling system. To rectify this, you’ll need to flush the system.  

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