Your Coolant and Antifreeze FAQs Answered

Have a question about what coolant/antifreeze is, why your car needs it, and how to use Prestone Coolant/Antifreeze? Our FAQs give you all the information you need to guarantee maximum protection for your car’s engine and cooling system.

What is coolant/antifreeze and how does it work?

Coolant/antifreeze is a mixture of antifreeze agents and water that circulates through your car’s cooling system to regulate the temperature of the engine. It prevents the engine freezing in the winter while also providing year-round protection from overheating.

Coolant/antifreeze contains ethylene glycol, an organic compound that provides antifreeze protection and increases the boiling point of water. That means, when used in a cooling system, it works to prevent freezing in cold temperatures while also protecting the engine from extreme heat, which would otherwise damage internal components.

The variant of ethylene glycol more commonly used in coolant/antifreeze is monoethylene glycol, or MEG. Odourless and colourless, it offers excellent antifreeze properties but should always be kept away from children and animals due to its sweet taste and toxicity.

Prestone Coolant/Antifreeze contains a premium formula that guarantees protection in extreme conditions from -37°C to +129°C.

How do I use Prestone Coolant/Antifreeze?

Just like checking your oil or your tyre pressure, making sure your car’s coolant/antifreeze is protecting your car as it should be is an important part of vehicle maintenance. Without it, you run the risk of overheating since there’s nothing to absorb the heat produced when the car is in use.

Fortnightly check-ups are something we really recommend at Prestone, to see if the coolant/antifreeze needs topping up and also to test if it’s protecting your vehicle.

If you find that you need to top it up, here’s a helpful guide.

  • Start by locating the coolant/antifreeze reservoir. This is usually visible on either side of the engine bay under the bonnet and is identifiable by the brightly coloured liquid inside.
  • When adding coolant/antifreeze, it’s important to ensure the engine has cooled before unscrewing the cap of the expansion tank as the coolant operates at around 90°C.
  • If you are using a Ready to Use Prestone Coolant/Antifreeze, it should be added straight into the cooling system through the expansion tank.
  • Locate the ‘min’ and ‘max’ markers on the side of the coolant expansion tank. Ideally the fluid level should be kept at the ‘max’ marker at all times.
  • After filling with Prestone Coolant/Antifreeze, make sure that the cap of the expansion tank is replaced and tightened.

What does the cooling system do?

The cooling system is designed to remove heat from the engine and keep it running at an optimum temperature. The system comprises a radiator, fan and hoses which run around the engine block, allowing the coolant/antifreeze to absorb heat from every part of the engine.

This heat is then dispelled in the radiator thanks to the volume of cold air coming in through the front grille and fan, and the liquid recirculated to absorb more heat. As the process is continuous, this ensures that the engine is always running at the correct temperature.

How do I identify my car’s coolant/antifreeze reservoir?

Your car’s coolant/antifreeze reservoir should be easy to identify by its coloured lid, with many cars having a yellow coolant/antifreeze cap. You’ll probably find that there’s a warning symbol on the cap too, which highlights the danger of unscrewing the cap when the engine is running or hot.

Engine coolant reservoir tank in a modern vehicle.The reservoir itself is usually made of thick, semi-translucent white plastic, and you should be able to see the coloured coolant/antifreeze (often pink, yellow, or green) through the side of the tank.

If you’re struggling to find your car’s coolant reservoir, the best thing to do is refer to the owner’s manual, which will have a diagram showing different parts and components under the bonnet. If you no longer have the manual, head online and visit the manufacturer’s website or forums dedicated to the make and model of your car — a fellow motorist should be able to point you in the direction of the coolant reservoir for your specific type of car.

How to check the level of the cooling system?

Checking your coolant/antifreeze level is a simple process and should only take a few minutes every couple of weeks.

To check your car’s coolant/antifreeze level, find the reservoir and check the fluid against the minimum and maximum markers imprinted on the side. The colour of the coolant/antifreeze should make this easy to do, but you may need to give the bottle a wipe to see the markers clearly.

Ideally, the level should always be closer to (or directly on) the ‘maximum’ mark, so if it’s dropped towards ‘minimum’, we’d recommend topping it up.

When adding any liquid to your car such as Prestone Coolant/Antifreeze, it’s important to ensure the engine has cooled before unscrewing the cap of the expansion tank as the coolant operates at around 90°C. After filling, make sure that the cap of the expansion tank is replaced and tightened.

If the level is below the minimum line, top it up to the maximum line and monitor on a daily basis. If it keeps dropping, you’ll need to check for leaks or get a mechanic to check for you.

Should I use ready to use coolant/antifreeze or concentrated?

Prestone Ready to Use Coolant/Antifreeze is specifically developed to offer an easy and convenient way to top up your vehicle’s cooling system. The Ready to Use formula can be added to your coolant reservoir directly from the bottle, whilst the Concentrated alternative will need to be mixed with water prior to use.

Both Ready to Use and Concentrated versions of the Prestone Coolant/Antifreeze are supplied in an easy-to-pour-bottle, making it simple to top up the coolant yourself.

Can I add Prestone Coolant/Antifreeze to other coolants?

Yes. Thanks to its unique and patented formula, Prestone Coolant/Antifreeze can be safely mixed with another product within the cooling system without causing damage or gelling. It’s also guaranteed to be compatible with all cars, vans, or light trucks.

That means there’s no need to flush your car’s cooling system before adding Prestone Coolant/Antifreeze. Simply pour the product into your coolant reservoir – it’s that easy.

Does coolant expire?

Generally, no. A sealed bottle of coolant/antifreeze has a 10 year shelf life, while an opened bottle can be stored safely for years and years without spoiling. As such, you’re unlikely to see an expiration date on any coolant and antifreeze-containing engine fluids.

With that said, it’s important to store coolant/antifreeze safely while adhering to the instructions on the product packaging. The fluid should remain in its original container and not be exposed to extreme variances in temperature. Ensure that the lid is securely fastened at all times, too, or it could present a hazard for children as well as animals.

Can you use car coolant in a motorcycle?

Yes, you can, so long as the coolant/antifreeze you’re using is based on ethylene glycol and is free from silicates. Some car coolants contain silicates and other compounds that can be harmful to motorcycle engines, so it’s super important that you read what a product contains before adding it to your bike.

If in doubt, always refer to your motorcycle’s manual, where you’ll find information on the correct type of coolant/antifreeze to use.

What happens if you overfill the coolant reservoir?

Overfilling your car’s coolant/antifreeze expansion vessel isn’t a good idea. Not only can it interfere with the pressure within the system, but it can also render the filler cap ineffective while also potentially interfering with the electrics.

On some cars, an overflow facility will drain excess fluid from the cooling system automatically. However, we wouldn’t run the risk. It’s better to manually siphon excess fluid from the system until the level sits at the ‘max’ fill line; you can do this easily with a household kitchen baster or a coolant/antifreeze tester.

Can I mix tap water with coolant?

You can in a pinch, but it’s much better to use distilled or de-ionised water. That’s because regular tap water contains minerals that can form hard deposits within the cooling system, increasing the risk of premature wear and tear of internal components, as well as reducing the lifespan of the coolant/antifreeze itself.

Find out more about Prestone Coolant/Antifreeze and other products in our high-performance car maintenance range here.