Everything you need to know about engine coolant
Engine coolant is just water, right?
Wrong. Engine coolant is actually a mixture of antifreeze and water (the ratio can vary from vehicle to vehicle). It’s not just for keeping cool either; engine coolant ensures that the water in your vehicle’s radiator system does not freeze in winter, or boil and evaporate in summer.
A 50:50 mix of antifreeze and water is most common – this raises the boiling point of water to between 240°C and 270°C, and lowers the freezing point to around -37°C. But don’t be tempted to fill up with pure antifreeze… pure antifreeze actually has a much higher freezing point at around -20°C.
Why do cars need coolant?
Nearly one third of the energy produced by the engine ends up as waste, either through the exhaust or as excess heat energy. This excess heat energy must be cooled quickly to prevent engine overheating and a subsequent breakdown.
Coolant is pumped through the engine cooling system, where the water absorbs excess heat energy which is then carried through to the radiator. Through a process of heat exchange, the heat is removed and the water is cooled before it circulates the system once more.
With coolant in the cooling system, the water doesn’t freeze or boil under extreme temperatures – meaning that the engine can be cooled effectively in any weather.
How often does coolant need replacing?
Antifreeze in itself does not expire, however the additives that prevent engine corrosion do. Therefore, the coolant must be changed to the manufacturer recommended guidelines, which for some vehicles is every 30,000 miles.
It’s always good to check that your coolant level is within the min/max marks on the coolant expansion tank. This can easily be done while you are under the bonnet checking washer fluid and engine oil levels. It can also be easy to confuse coolant with washer fluid, but be careful, these are two very different lubricants.
If the coolant level is below the minimum mark, this could indicate a leak as most modern cars, vans and commercial vehicles have sealed engine cooling systems. In this case, you should seek advice from a professional workshop, before more costly engine problems develop.
How do I replace/refill my coolant?
If you do decide to refill with coolant yourself, there are a few things to think about.
Firstly make sure you replace like for like, as different types of antifreeze don’t tend to mix well. You should also double check in your manual which is the coolant filler cap, it can be an expensive mistake to put coolant in the washer fluid or engine oil tank, so it’s worth making sure you’re in the right place.
Finally, NEVER remove the coolant filler cap while the engine is hot; coolant does get very hot, and high engine pressures mean that releasing this cap when the engine isn’t cold could cause hot coolant to gush from the tank and scold you.
What are Total’s coolant and antifreeze products?
Total offers a full range of ready-mixed coolant, TOTAL COOLELF, and antifreeze concentrate, TOTAL GLACELF, which must be diluted with water. Having been developed in our advanced research centres, our range is fully approved by leading vehicle manufacturers and is available in various different quantities.
Visit our vehicle antifreeze and coolants page to find out more about Total’s high quality products for cars, vans and larger commercial vehicles such as trucks, HGVs and coaches.