How to top up your engine coolant

Filling up your engine coolant for the first time? Check out our guide on what to do.


By Marmalade Author

Updated on May 30th, 2024

How to top up your engine coolant

During the winter months, your car might need a bit more TLC than usual. One thing you need to stay on top of is your engine coolant.

Coolant, more commonly known as antifreeze, is a mixture of ethylene or propylene glycol and water, usually in a 50/50 ratio. Keeping it filled up is easy (like topping up your oil or screenwash), but it does require a bit of caution because using the wrong substance could cause irreparable damage to your vehicle.

We’ll talk you through how to do it safely and correctly. We always recommend looking at your car’s handbook beforehand, this will help you identify the specific type of coolant required and how much is needed.


Wait until the engine is cold

coolant tank
It’s extremely important that you wait at least 3 hours after using the vehicle for the engine to cool down. Pressurised water may escape the reservoir when you unscrew your coolant cap, if the engine is hot then this can scald the skin so please be careful.

Find the coolant reservoir

Your car’s handbook should explain where to find the reservoir and also what kind of anti-freeze to put in it. This is really important to get right before attempting to top up your coolant.

Check the minimum & maximum lines

The amount of coolant should always be sitting somewhere between these lines. This gives you a guide of where to fill it to.

Create your mixture

You can buy it pre-mixed but if you feel comfortable making your own it’s always best to mix the antifreeze with distilled water before you put it in. Most labels recommend half and half as a measurement.

Unscrew and fill

Make sure you use a rag or thick cloth when unscrewing the coolant cap. Using a funnel to prevent spillages, pour the liquid in. You want to avoid getting any coolant on the skin or floor as this can be poisonous to humans and animals. Once you see the liquid reach the maximum line, screw the cap back on until you hear it click.

Need insurance as a new driver?

Car insurance for new drivers isn’t one size fits all. Answer three quick questions and we'll help you find cover that works for you!

Parent advice

Advice and guides for parents helping their learner driver on their driving journey.

black box myth busters

Black Box Mythbusters

There’s a lot of misconceptions around driving with a black box – we’ve got the facts on what’s true and false!

friends happy on phones

Visit the Driver Hub

Check out the latest stories and blogs from young drivers

ICS member logo
Customer Service Excellence Awards
BIBA scheme provider logo
First car award 2019 winner logo