6 minute read|13th Jan 2026
It is necessary for all drivers to keep their vehicle running smoothly and as efficiently as possible. A crucial part of your car maintenance – the engine coolant – is often overlooked, yet vitally important.
Also known as antifreeze, coolant plays a pivotal role in regulating your engine's temperature in both hot and cold weather. Therefore, no matter what time of year, it is something all drivers should be regularly checking.
This guide looks at what engine coolant does to your vehicle, what to look for if it is leaking, and how to repair common problem.
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Engine coolant is a fluid added to the engine's cooling system that helps regulate its temperature.
It plays a vital role in maintaining the engine's temperature within the optimal range of the specific make and model, preventing it from overheating or freezing. It is something that helps keep a car in the best condition possible year-round.
Most coolants are pre-mixed with anti-freeze, but you should check the label to ensure this is the case. The coolant is a mixture of water, ethylene glycol or propylene glycol – or a combination of the three. All drivers should regularly check coolant and top up as needed.
Always refer to the vehicle's owner's manual for specific recommendations regarding the type of coolant to use.
If you are unsure what is the best coolant for your car, speak with a mobile mechanic or your local approved garage.
Poor maintenance, driving without servicing, plus general wear and tear are all linked to coolant leaks.
Coolant leaks are specifically caused by:
The primary function of engine coolant is to regulate the temperature of the engine.
During combustion, the engine generates a significant amount of heat, which the coolant absorbs and carries away from the engine to prevent it from overheating.
It also contains antifreeze properties, such as ethylene glycol or propylene glycol, which prevent the liquid from freezing in colder temperatures.
The fluid also helps maintain a healthy engine with corrosion inhibitors that protect the various components of the cooling system, such as the radiator, water pump, and engine.
By extending the life of these components, it will save the owner a large bill to fix these issues – which can end up being quite expensive.
Car ownership comes with many challenges, and regular maintenance is something everyone should be doing.
Coolant circulates through the engine and absorbs heat generated during the combustion process, and the continued use of the engine throughout the length of the drive.
The fluid in the coolant system carries the heat to the radiator, where it dissipates into the air – therefore regulating the temperature and keeping the engine in optimal condition.
It also provides a safety feature of keeping the engine from overheating. However, in colder, wintry weather, the anti-freeze part of the fluid prevents the coolant from freezing.
The RAC recommends regular oil changes to help keep your engine running smoothly
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If your car is losing coolant, don’t ignore it. A small leak can quickly lead to overheating, and repeated overheating is one of the fastest ways to cause major engine damage. Stop driving and get the system checked before the problem escalates.
Nick Mullender
Lead RAC Mobile Mechanic
Driving with a coolant leak can cause serious damage to your vehicle. This includes:
Some vehicles will have low coolant car dashboard warning light which will look like a thermometer in liquid. It is not recommended to wait until this warning light is illuminated before checking your coolant, as the engine may have already suffered severe damage by the time this symbol appears on your vehicle's dashboard.
Knowing what to do if your car is overheating is important for all car owners.
If the engine of your vehicle is leaking coolant then you should have it inspected by a professional mechanic. Due to the risk of overheating and breakdown, a car with a coolant leak may not be safe to drive. In this instance, call a mobile mechanic.
In some cases, it may be possible to repair the coolant leak. A qualified professional should be trusted to carry out the following steps:
The engine must be running, but the coolant must be cold when carrying out the fix. If this doesn’t resolve the issue, then the radiator will need to be removed and either have more extensive work done on it – or it will need to be replaced.
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Engine coolant leaks can be quite simple fixes. Prices can range from around £50 to £300, depending on the make, model, age, and type of vehicle.
If the radiator needs to be removed and have more extensive work carried out to fix the issue, then the bill could be more than £1,000.
Replacing a car radiator can range from £400 to more than £2,000.
If you are looking to top up the engine coolant in your car, then it is important to get the correct one for your vehicle.
Check your car owner’s manual, which will outline the types that your engine can use.
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