What is antifreeze?

Antifreeze is an additive that stops the water in your engine’s cooling system from freezing, by lowering its freezing point. Not just that, it also does a number of other important jobs, making it a vital car fluid to keep your engine running smoothly.

Why does my car need antifreeze?

Your car’s cooling system is responsible for carrying excess heat away from the engine to keep it at the optimal operating temperature. If the coolant doesn’t contain antifreeze, it may freeze in cold conditions, leading to some serious and costly damage to your radiator and other key components.

Antifreeze also does several other jobs alongside lowering the freezing point of your engine coolant; it raises the coolant’s boiling point to prevent overheating, protects your engine from corrosion, aids heat transfer, and prevents an internal build-up of scale.

For help with adding antifreeze to your engine, take a look at our guide to preventing overheating.

What types of antifreeze are there?

There are three main formulations of antifreeze, which can all come either ready-mixed or in a concentrated form. Pre-mixed antifreeze is commonly referred to as engine coolant, and can normally be used straightaway for top-ups and replacements. The concentrated form needs to be diluted with water, at a level of around 50% antifreeze and 50% water. Always check the instructions for the right ratio to use.

As for different formulations, there are three basic types of engine coolant – IAT, OAT, and HOAT. They each serve different purposes, and are used for specific types of vehicles:

Inorganic Additive Technology (IAT)

IAT is the traditional coolant used in older cars, filled with inorganic additives that provide fast-acting corrosion resistance. However, it’s now rarely used as the default in modern cars, since these additives deplete quite quickly, resulting in a short lifespan for the coolant.

The liquid is usually bright green and will need changing roughly every 2 years or 24,000 miles.

Organic Acid Technology (OAT)

OAT coolants are used for most cars manufactured after 1998 and last a lot longer than IAT coolants thanks to the lack of silicate additives. Instead, they use organic acids and corrosion inhibiters, which, while increasing the coolant’s lifespan, does give it lower corrosion resistance.

OAT coolants are typically orange, red or pink in colour, and won’t need to be changed for around 5 years or 50,000 miles.

OAT coolant is also more popular in modern cars due to changes in the manufacturing. While IAT coolant works best in older engines made of steel and iron, OAT coolant is better suited to aluminium engines, which is what most modern cars are made of.

Hybrid Oat Acid Technology (HOAT)

This coolant combines the properties of IAT and OAT to create a fusion that gives you the best of both worlds; the anti-corrosion properties of IAT coolant and the long life of OAT coolant.

The liquid is usually yellow in colour and should last around five years or 50,000 miles.

Where can I buy antifreeze?

Here at Halfords, we have a range of antifreeze available both online and in-store, so you can find the perfect match for your vehicle quickly and easily.

If you're unsure about which antifreeze to choose, you can enter your registration number online to be matched with the best option for your vehicle, or you can drop by your local Halfords where one of our experts will be more than happy to help.

To save yourself some time and effort, why not book in for our 10 point car check? We’ll check your coolant alongside a host of other essential areas such as your tyre depth, tyre inflation level, screen wash level and battery health.

Shop all antifreeze

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