Antifreeze and coolant are terms often used to describe the same thing. They both refer to the liquid that helps your engine run at the right temperature. The main difference between antifreeze and coolant is when they are most effective. The engine needs to be cooled all the time, no matter the weather, but having antifreeze properties during the winter keeps the coolant from freezing.

Now that you understand why the same thing has two different names, we're going to dig deeper into the antifreeze properties of coolant. What do they do and why are they so important? By the end of this article, you will understand:

  • What antifreeze is made of
  • Its many roles in your engine
  • How to identify the correct antifreeze for your car
  • Which manufacturers use which antifreeze
  • How to change your antifreeze and coolant yourself (or how to get a professional to do it for you)
  • And more!

 

Glossary

Ethylene Glycol - A sweet-tasting, odourless and colourless liquid used as an organic compound in antifreeze and polyester fibres. It is made of 6 parts Hydrogen, 2 parts Oxygen and 2 parts Carbon (C2H6O2).

Propylene Glycol - A nearly odourless, colourless synthetic liquid that absorbs water. It is used as an additive in certain medicines, cosmetics or food products, as well as antifreeze. It is non-toxic and recognised as generally safe by the Food and Drug Administration (FDA). It is made of 3 parts Carbon, 8 parts Hydrogen and 2 parts Oxygen (C3H8O2).

HOAT - Hybrid Organic Acid Technology. A form of antifreeze with an extended lifespan. It is created by mixing the other two forms of antifreeze together.

IAT - Inorganic Acid Technology. An older form of antifreeze, commonly found in older cars. Made with ethylene glycol and usually highly toxic.

OAT - Organic Acid Technology. The common antifreeze found in modern cars, it provides high-temperature protection for aluminium. Made with propylene glycol and much less toxic.

 

Summary

Antifreeze is a concentrated additive made of ethylene or propylene glycol that stops the water in your car's cooling system from freezing. It also protects your car's hydraulics from wear and tear and increases the boiling point of coolant to help it deal with the high engine temperatures that it has to perform under.

Antifreeze is most useful during the winter, but it also offers protection all year long. Each manufacturer uses a different type of antifreeze and, while the colours are more of a marketing tactic than anything important, they do help you choose the right one. You should always consult your vehicle handbook when it comes to changing coolant and antifreeze or book an appointment at a garage near you to have a professional do it for you.

 

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What is Antifreeze?

Antifreeze is a concentrated additive that stops the water in your car's cooling system from freezing. It is a must-have during winter as our cars must work in freezing temperatures. As water freezes at 0° Celsius, ice would form in our car's pipes, render them useless and cause potential engine damage!

 

What is Antifreeze Made Of?

The main ingredient in antifreeze is ethylene glycol or propylene glycol. This is the same base ingredient as coolant.

Ethylene glycol is highly toxic and commonly used in older cars, whereas propylene glycol is much less toxic and is widely used in modern cars.

 

What Does Antifreeze Do?

While antifreeze's main job is to lower the freezing point of water in your cooling system, it does a few other jobs as well. These are:

  • Increasing the boiling point of the liquid, allowing for higher coolant temperatures
  • Protecting your car's hydraulic circuit from wear and tear
  • Preventing pipes bursting from expansion
  • Preventing engine coolant from getting too hot and boiling inside the engine

Antifreeze is a solution to the problems with using water as a fluid for heat transference. These are its relatively low boiling point compared to common engine temperatures and high freezing point.

 

When Do I Need to Add Antifreeze Into My Car?

Unsurprisingly, antifreeze is most useful during the winter. Most good quality coolants have antifreeze properties as standard (as they are a diluted form of antifreeze) but they don't offer enough protection when the weather turns really cold.

Of course, there's nothing wrong with using antifreeze to protect your car's engine all year, especially as this means you don't have to remember to add it when winter rolls around.

 

driver adding pink antifreeze into coolant reservoir of car

Antifreeze goes into the coolant reservoir, even if you add it on its own. However, you must make sure you choose a suitable type for your car.

 

What is the Correct Antifreeze For My Car?

Your car is designed to use a specific type of coolant with a specific freezing point. It won't work properly if you mix two or more different types.

Antifreeze comes in many different colours and has a range of names. The colours are not the most important factor (they're just a marketing tactic) but they can help you identify the correct type. The main types are HOAT, IAT and OAT, each of which works slightly differently.

Below are the most common colours used by popular manufacturers. These can provide a rough guide but we would strongly recommend checking your vehicle handbook for specific advice on which to use in your car.

 

Ford

Ford recommends using Motorcraft antifreeze. There are different colours to use depending on how old your vehicle is:

  • Pre-2002 = Fluroescent Green
  • 2002-2010 = Yellow
  • Selected 2009-2012 = Dark Green
  • 2012-Present = Orange

 

BMW

All BMW vehicles use a blue HOAT antifreeze with no nitrates or phosphorate.

 

Mercedes-Benz

Mercedes use a HOAT antifreeze. It is blue for vehicles registered before 2014 and pink for vehicles registered after 2014.

 

VW, SKODA, Audi & SEAT

As these brands are all owned by the Volkswagen Group, they all use the same type. The VW Group recommends using an anti-phosphate, anti-nitrate and anti-phosphorous antifreeze. This can be either:

  • G11 (Blue or Blue-Green)
  • G12 (Red or Pink)
  • G12+/G13 (Violet)

 

Renault, Peugeot & Citroen

All three French manufacturers use Type D antifreeze. This is green in colour.

The only exceptions are for Peugeot 107 and 108 1.0 essence models and Citroen C1 I and IL 1.0 essence models. If you own one of these, check your vehicle handbook for the specifics.

 

Kia

Green is the factory fill colour for Kia vehicles.

 

Vauxhall, Fiat

General Motors own both manufacturers, so they use the default GM type. This is generally red but can also be orange.

 

Toyota

Toyota vehicles use either red, orange or pink antifreeze.

 

Nissan

Blue is the factory fill colour for Nissan vehicles. Some pre-2009 models may need green antifreeze.

 

Hyundai

Hyundai vehicles can use G11 (Blue or Blue-Green), G12 (Red or Pink) or G12+/G13 (Violet) antifreeze.

 

Honda

Honda vehicles have used blue antifreeze since 2004 and green pre-2004. You can put blue on top of green but not the other way around.

 

MINI

MINI vehicles use a blue HOAT antifreeze with no phosphates or nitrates.

 

Mazda

Mazda vehicles now use a green FL22 antifreeze. This is compatible with previous Mazda models.

 

If your manufacturer has more than one colour available, you should always refer to your coolant reservoir. Use the same colour liquid that's already in it.

 

How Do I Change My Antifreeze

As coolant and antifreeze mix together, you have to change them together as well. You should only attempt to change yours if you feel confident doing so. Before you start, make sure you have taken the following precautions:

  • You must fill your reservoir mostly with coolant. Your coolant needs antifreeze properties, but you mustn't add antifreeze on its own. As we mentioned earlier, you won't be able to properly protect your car in all conditions. Make sure you've checked the label on the bottle thoroughly before adding any liquid.
  • The coolant must be cold. It boils while your engine is in use, so can scald you and/or cause damage to the radiator block if you try and change it while warm.
  • Wear gloves and goggles. Antifreeze is highly corrosive, even the non-toxic propylene glycol. Have water handy to rinse off any spills, either on yourself or the painted surfaces of your car.
  • Keep antifreeze away from children and pets. It smells very sweet, which encourages young children and animals to drink it. This should not happen under any circumstances.

To change your antifreeze, you must:

  1. Raise the front of your vehicle on a jack and place jack stands beneath the car.
  2. Lower it into place, taking care to place chocks behind your back wheels. This stops your car from rolling backwards.
  3. Remove an underbody shield (if applicable).
  4. Place a container under the radiator and undo the drain valve. Your vehicle handbook will show you where this is.
  5. Flush the system as many times as necessary to remove all the old coolant. Make sure you find the reserve tank, remove it and drain any remaining coolant as well.
  6. Put the tank back in place and replace the drain valve.
  7. Refill the system with the correct type of antifreeze. Make sure you don't fill past the maximum line.

You may need to run the engine briefly, top up the coolant, replace the radiator cap and then run the engine again until the cooling fan turns on. Check the coolant levels again and top up if needed.

 

How Do I Dispose of Antifreeze

You must dispose of used antifreeze at an official disposal site. This is usually found at a local recycling centre. You must not dispose of it on the ground or down a drain.

Before changing yours, make sure that you know where your nearest disposal centre is and that you're able to transport it there securely.

 

Is There Not an Easier Way?

If you're not sure how to change your coolant yourself, you can book an appointment at a garage near you. During the appointment, a professional mechanic will complete the same process as above to the highest standard and use the correct type of antifreeze. They will also check for any leaks or other damage to ensure your car is in top condition.

You should change your antifreeze every 2-5 years. If it has been a while since yours, enter your vehicle reg and postcode to compare instant prices on a coolant change near you. Filter by availability, price, distance, additional services offered or reviews and ratings - whatever matters most to you. You should also book an appointment if yours looks brown, a different colour to what is recommended or has lumps floating in it.