Antifreeze: what is it, colours and how to use

There are several vital fluids that are needed to keep your vehicle in good working order – and one of them is antifreeze. But what is it? And why is it important?

Regularly checking your vehicle can help you stay on top of coolant levels, but there is a lot more that antifreeze does to help keep the engine working.

This car maintenance guide explains the different variations and how to put it into your vehicle.

What is antifreeze?

Antifreeze is a liquid used in the cooling systems of vehicle engines to prevent the coolant from freezing in cold temperatures and from overheating in hot temperatures.

It is typically a mixture of water and chemicals, such as ethylene glycol or propylene glycol, which have properties that lower the freezing point and raise the boiling point of the coolant.

This fluid is an important part of ensuring that the engine stays in its ideal operating temperature.

Antifreeze prevents the coolant from freezing in cold weather, which would otherwise cause it to expand and cause damage to the engine, radiator and the rest of the coolant system.

It also helps prevent overheating in hot weather by raising the boiling point of the coolant, allowing the engine to operate at higher temperatures without the risk of overheating.

An added benefit is that it provides corrosion protection by containing additives that protect the engine's cooling system components, such as the radiator, water pump and hoses, from corrosion.

Included in the mixture are chemicals that help lubricate parts within the cooling system.

What does it do and why does my car need it?

Antifreeze prevents your car’s engine from freezing in cold temperatures and from overheating in hot temperatures.

It works by lowering the freezing point and raising the boiling point of the coolant.

A car needs antifreeze to maintain proper engine temperature and protect the cooling system from damage.

By topping it up regularly, it ensures that the engine runs efficiently in all weather conditions.

Is antifreeze the same as engine coolant?

No, antifreeze and engine coolant are not the same – but do have similar properties and are usually used together. Antifreeze is a key component of engine coolant, which is a mixture of antifreeze and water.

The coolant regulates the engine temperature, preventing freezing in cold weather and overheating in hot weather, while also protecting the system from corrosion.

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Which type of antifreeze should I use for my car?

There are three main variants of antifreeze available in the UK:

Green antifreeze

Green antifreeze is a traditional, older type of coolant available to drivers.

It is often made from ethylene glycol and was very popular in the 1990s.

This version contains additives to prevent corrosion, freezing and overheating, but as it’s an older formula it usually needs replacing more often than other types of antifreeze.

Orange antifreeze

Orange antifreeze, often made with organic acid technology (OAT), is designed for newer vehicles.

Unlike green or red coolants, it lasts longer and doesn't need to be changed as frequently.

It's important to use the correct type for your vehicle, as mixing it with other coolants can cause damage to the engine.

Red antifreeze

Red antifreeze is typically made a hybrid organic acid and is designed for modern vehicles.

It provides excellent corrosion protection for all engine components.

It also lasts longer than traditional green coolant, requiring fewer changes.

What are emergency alternatives to use?

The aim as a car owner to always stay on top of topping up fluid and coolant levels – but sometimes I can slip our minds.

This is why there are some short term, emergency alternatives.

However, these should not be used regularly.

The first is to use water – however, this should only be in the warmer months as it can freeze. It should only be used temporarily and replaced with proper coolant, however, as it can corrode engine components if left unchanged.

The other option is a makeshift home-made antifreeze mixture of water and ethylene glycol.

However, it is strongly recommended to speak to a mechanic, rather than just adding it to an engine.

Using the wrong fluids can lead to expensive repairs.

Where to put antifreeze in your vehicle

To add antifreeze to your vehicle, locate the radiator or coolant reservoir, usually marked with a symbol of a radiator cap.

Remember that it is important to ensure the engine is cool before opening the cap.

You’ll then need to pour the antifreeze mixture into the reservoir or radiator until it reaches the recommended level.

Be sure to use the right type of antifreeze for your vehicle and avoid overfilling, as it can cause leaks or engine damage.