What Coolant Should I Use for My Car?
Ellie Dyer-Brown, 2 months ago
5 min read
- Maintenance
FixMyCar discusses the different types of coolant and how to find the right one for your car.
Not all coolants are created equal. There are different types, and using the wrong one can negatively impact your car's health in the long term.
With so many coolant colours and labels around, knowing which one you need can be confusing - but it doesn't have to be. This guide simplifies the information you need to use coolant with confidence.
Contents
Is coolant the same as antifreeze?
In a nutshell: The most common type of coolant is made with inorganic acid technology (IAT) antifreeze. You should check your owner's manual to find out which antifreeze is right for your car.
What is coolant in a car?
Like your body, your car has an optimum operating temperature that must be maintained to keep it running smoothly and prevent damage. Without a cooling system, it would quickly overheat. But where does the heat go, and how? That’s where coolant comes in.
Coolant is a liquid that removes heat from the cooling system and engine. It also stops water in the system from freezing in cold weather conditions. It’s usually made of glycol-based chemicals (antifreeze) and water. Sometimes, it contains additives like rust inhibitors and dyes.
Is coolant the same as antifreeze?
Antifreeze and coolant are very similar. Antifreeze is a concentrated glycol-based liquid that lowers the freezing point and raises the boiling point of engine coolant. It often needs diluting with water before it can be added to the system. Once you add water, the mixture becomes coolant.
Types of antifreeze
There are a few different types of antifreeze to be aware of, differentiated by their chemical composition and colour:
IAT (Inorganic Acid Technology) - organic acids - green
OAT (Organic Acid technology) - silicates - orange, red or pink
HOAT (Hybrid OAT) - silicates and organic acids - yellow
P-HOAT (Phosphated HOAT) - phosphates and organic acids - blue, red or pink
Si-OAT (Silicated HOAT) - silicates and organic acids - purple
HOAT (Hybrid OAT, Phosphate-free) - amine, nitrite and phosphate (NAP)-free - turquoise
You shouldn’t buy antifreeze based on colour alone because manufacturers may use different colours for different types. The best thing to do is familiarise yourself with the exact type of coolant your car needs, such as OAT or IAT.
What coolant for my car?
The vehicle handbook is the best place to search for information about your car. It will provide advice about the type of coolant you need and may also suggest a particular brand for optimal performance.
| Car manufacturers | Coolant type |
|---|---|
| Older models (before 1998) | Green IAT |
| BMW, Tesla, Volvo and MINI | Turquoise HOAT phosphate-free |
| Saab, General Motors and Volkswagen | Orange OAT |
| Ford, Chrysler and other European models | yellow HOAT |
| Toyota, Nissan, Suzuki and other Asian models | Pink or blue P-HOAT |
| Mercedes, Porsche and Audi | Purple Si-OAT |
The above table is for guidance only. Always double-check your vehicle handbook for the correct information and read the coolant label carefully before buying and using it.
How much coolant does my car take?
A car's coolant system typically holds three to six litres, and cars with bigger engines may need even more. Check your vehicle handbook to find out the exact capacity of your model.
You can tell when your car's coolant is at the right level by opening the bonnet and looking at the reservoir. It will show a maximum and minimum fill line, and the coolant should sit between them. Avoid driving until you've topped it up if it's too low.
Where can I buy coolant?
You can buy coolant at motoring supply shops and most petrol stations, though the options are sometimes limited if you get it from a fuel station. Always buy the correct coolant for your vehicle. Another option is to purchase coolant online, where you can shop around for the best deal.
Can I refill coolant myself?
Topping up coolant is an essential part of car maintenance, and you can easily do it yourself. This guide explains how. Make sure you read the instructions on the bottle carefully to see whether it needs diluting before you put it in the system.
Always wait until your engine is completely cool before topping up the coolant.
If you'd rather have a mechanic check and change your coolant, FixMyCar can help you find a trusted local garage.
What happens if I use the wrong coolant?
Using the wrong coolant for your car isn’t optimal, but it won’t cause immediate damage. However, in the long term, it can lead to corrosion, harming parts like the water pump, gaskets, seals, and radiator hoses.
Although driving around with the wrong coolant is fine for a while, you should aim to have the system flushed as soon as you have the time and money for it. For most of us, our cars represent a significant investment that is worth protecting by using the right fluids.
It’s best to avoid mixing two different types of coolant because it can stop the corrosion inhibitors from working and turn the coolant into a gel-like substance, depending on how the chemicals interact. If you think this has already happened, contact a mobile mechanic who can come to your location and flush the system without needing to drive anywhere.
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Written by Ellie
Ellie is FixMyCar's Content Writer. She has over three years of experience writing about cars and regularly collaborates with automotive experts to provide trustworthy advice for drivers that is easy understand. Her work has been featured in Yahoo! Finance, iNews, The Daily Express and The Sun. She has a BA in English literature and an MA in creative writing from Durham University. Outside of work, Ellie follows F1 and eagerly awaits Ferrari's next era of dominance in the sport. She drives a Suzuki Swift.