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Antifreeze: a guide to what it is, its types, and how to use it 

Antifreeze and coolant are deeply important to the safe and efficient running of your vehicle. Without them, your car will overheat or freeze up, and even before that happens, your components can be wracked by extreme temperatures, corrosion, and a whole host of other issues - all problems that Total GLACELF antifreeze aims to prevent. 

It’s important to learn what antifreeze is, its types, the differences between them, and how to use them effectively. Scroll down for answers to all these questions and more. 

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What is antifreeze? What does it do 

Antifreeze is an automotive fluid that, when mixed with water, creates coolant - a crucial substance that flows within car engine cooling systems.  

What does antifreeze do? Well, antifreeze reduces the freezing point of the coolant in the car, protecting the fluid from freezing up in sub-zero temperatures. When water is added, antifreeze boosts the boiling point of the liquid, allowing it to travel through the car’s cooling system, absorbing heat from the engine and its components - more than would be possible if pure water was used. 

Antifreeze is usually made from either ethylene glycol (also known as monoethylene glycol) or propylene glycol. Antifreeze has a lower freezing point and higher boiling point than water, but when mixed with water, these capabilities are enhanced further, which is why antifreeze should never be used on its own. Typically, a 50-50 mix of antifreeze to water produces the most effective coolant for driving in temperate climates like the UK. 

Antifreeze and coolant are both toxic to animals and people due to the ethylene glycol or propylene glycol they are made of. That’s why it’s crucial to store them safely, well away from children and pets, and to clean up any spills immediately. 

 

What is the meaning of antifreeze? 

The meaning of the word ‘antifreeze’ perfectly describes the fluid’s capabilities: stopping the fluids in an engine’s cooling system from freezing. Put simply, it’s an anti-freeze liquid. 

 

What are the different types of antifreeze in the UK? 

 

We all need antifreeze coolant, but what are the different types available to drivers in the UK? Here are all the types you may encounter at your local garage, their specific type of corrosion inhibitor, and their (typical) colour: 

  • OAT (Organic Acid Technology) – Organic Acids – Orange or red 

  • IAT (Inorganic Additive Technology) – Silicates – Green  

  • HOAT (Hybrid OAT) – Silicates and organic acids – Yellow  

  • Si-OAT (Silicated HOAT) – Silicates and organic acids – Purple   

  • P-HOAT (Phosphated HOAT) – Phosphates and organic acids – Blue, red or pink 

  • HOAT (Hybrid OAT, Phosphate-free) – nitrite, amine, and phosphate (NAP)-free – Turquoise  

There are lots of different types of antifreeze colours too. These colours are due to the dyes used to clearly separate each type from the others, allowing drivers to quickly and easily learn and select which their car needs without needing to learn the specific chemical names of each. You can get red, blue, or green antifreeze, as well as many other colours. 

That said, different manufacturers of vehicle and antifreeze can use opposing colours to other manufacturers - making the difference between blue and red antifreeze difficult to gauge judging only using the colour. That means it’s crucial you know the exact type your vehicle needs, such as IAT or OAT. 

Learn more about which type of antifreeze to pick in our guide. 

Which antifreeze? 

How to dispose of antifreeze 

Due to its toxic nature, it’s important to dispose of antifreeze correctly - it can damage the environment and kill animals if you pour it down the drain.  

To dispose of antifreeze safely, contact your local recycling centre as there is a high likelihood they will be able to take the antifreeze off your hands and properly dispose of it - find yours here. Alternatively, you may be able to dispose of used or unwanted antifreeze at your local garage or workshop, however you may be charged a small fee.  

 

Where to put antifreeze in a car 

Antifreeze should be put in the dedicated coolant reservoir underneath your bonnet in the engine compartment.  

The reservoir should be relatively transparent compared to the metal parts surrounding it, with two lines on the side - the top marked ‘F’ (full), the bottom, ‘L’ (low); maximum and minimum may also be used. 

The screw cap on top of the reservoir may also be marked ‘Coolant’, or feature a stop sign surrounding a hand opening the screw cap - the latter is because you must always cover the cap with a rag when unscrewing the cap as extremely hot, pressurised steam may escape once you open it. 

To top up your antifreeze, follow our step-by-step guide below. 

 

How to top up antifreeze in a car 

From time to time, it’s important to top up the antifreeze in your car (after mixing it with the correct amount of distilled water, of course). To do so safely, follow these instructions: 

  1. Turn on your car for ten minutes 
  2. Park the vehicle and let the engine cool entirely. 
  3. Find the antifreeze coolant reservoir: the precise location will be noted in your car’s handbook 
  4. Check the reservoir level: if the liquid is below the ‘L’ or ‘minimum’ line, it’s time to top up. 
  5. Mix antifreeze to make coolant: following your handbook’s instructions, mix the correct ratio of antifreeze to distilled water.  
  6. Cover the reservoir cap with a cloth and unscrew it. 
  7. Place a funnel into the reservoir. 
  8. Slowly pour coolant down the funnel into the reservoir. 
  9. Stop filling when the level reaches the ‘full’ or ‘maximum’ marker. 
  10. Screw the cap back on until it clicks. 

Top up your antifreeze 

 Is antifreeze the same as coolant? 

Antifreeze and coolant are different fluids. Antifreeze is a concentrated liquid that must be mixed with distilled water before it’s added to the cooling system.  

If the ratio of antifreeze to water is incorrect, the cooling system will not work as efficiently, and you may encounter issues with your engine, like deposit formation or overheating. That’s because car manufacturers precisely build their car cooling systems to work with a set coolant ratio - use the wrong one and you could spell trouble. 

Learn about how antifreeze and coolant differ in our guide. 

Antifreeze vs. coolant 

 

The ultimate guide to antifreeze and coolant 

Antifreeze and coolant need to be used the right way if you want to keep your engine in pristine working order - saving you a penny or two in the process. 

First, each type of antifreeze and coolant has a specific corrosion inhibitor. This is the ingredient that stops the water in the coolant mix from corroding the parts within the cooling system.  

Corrosion inhibitors include Organic Acid Technology (OAT), Inorganic Additive Technology (IAT), Nitrated Organic Acid Technology (NOAT), and Hybrid Organic Acid Technology (HOAT). Different makes of cars use different types - your specific one will be noted in your vehicle handbook. 

It’s also a good idea to understand how to diagnose different problems with your antifreeze. In our ultimate guide, understand how to quickly check for antifreeze leaks, and see whether there is oil in your coolant - both bad for the health of your cooling system. 

For in-depth answers, view our ultimate guide to antifreeze and coolant below. 

Learn about antifreeze 

 

How to fix an antifreeze leak 

Antifreeze leaks are bad news for your car, increasing the risk of engine lock-up or overheating, but the fluid is toxic, so can be a danger to children and pets tempted by its surprisingly sweet taste. That means it’s crucial you identify and fix leaks quickly. 

In our guide to fixing antifreeze and coolant leaks, you can learn various ways to identify antifreeze leaks, how to find the sources of the leak within your engine and wider vehicle, and the steps needed to fix the problem. View the guide below. 

Fix antifreeze leaks 

 

Motorcycle coolant: the definitive guide 

Whether you travel two-wheeled throughout the week or enjoy opening up the throttle at the weekends, if you ride, your motorbike needs antifreeze and coolant just as much as any other engine.  

In our guide to motorcycle coolant, learn what antifreeze does within bike engines, how to top up and change bike antifreeze, how to choose the right one for you, how to store it, and more. Click the link below to learn more. 

Discover motorcycle coolant 

 

Choose TotalEnergies for your antifreeze and coolant 

With TotalEnergies’ GLACELF range of antifreeze, you can keep your engine running efficiently while safeguarding the components that form your car’s cooling system. Check out the range to learn more.