Engine Coolant change & replacement made easy

What does engine coolant do?

Engine coolant is key to keeping your engine at the right temperature. It flows through the cooling system, absorbing heat from the engine and preventing it from overheating during use.

Coolant circulates from the reservoir, through the water pump, radiator, and thermostat, then into the engine block. As the engine heats up, the thermostat opens to allow more coolant through, helping regulate temperature. Once cooled in the radiator, the fluid continues the cycle.

This constant flow helps maintain optimal engine temperature, supports efficient combustion, improves fuel efficiency and protects the engine from heat damage.

What does an engine coolant change job involve?

When it’s time to replace your engine coolant, a professional mechanic follows a this general process to keep your cooling system in top condition:
* The mechanic checks the coolant level and condition, and inspects the cooling system for any signs of leaks or contamination.
* Coolant will be drained and replaced with the correct type for your vehicle.
* In some cases, a cleaning solution may be added, the engine run briefly, and the system flushed to remove sludge or residue.
* The mechanic drains the full cooling system to clear out any remaining old coolant.
* The system may be flushed with water and drained again (often twice) to ensure it’s completely clean.
* The engine is started and brought up to temperature to check for leaks and confirm everything is running smoothly.

How do I know when I need an engine coolant change?

There are a few warning signs that may indicate it’s time to replace your engine coolant:
* Some vehicles have a scheduled reminder for coolant service; if the ‘Maintenance’ light appears, it may be due.
* If the dashboard temperature light comes on, your engine may be running hotter than it should — possibly due to old or contaminated coolant.
* If your engine regularly runs hot or shows signs of overheating, the coolant may no longer be doing its job effectively.

If you notice any of these signs, it’s best to have your cooling system inspected by a professional mechanic.

What does the engine coolant warning light mean?

The engine coolant warning light is there to alert you if something’s wrong with your car’s cooling system, usually related to temperature or coolant level.

If the light appears blue (often in cold starts), it simply means the engine is still warming up. This is normal and should turn off once the engine reaches operating temperature.

A yellow or amber light typically means the coolant level is low. You should pull over safely, wait for the engine to cool completely, and top up the coolant with the correct type if needed.

A red warning light signals that the engine is overheating or the coolant is critically low. In this case, stop the car immediately, turn off the engine, and let it cool down. Continuing to drive could cause serious engine damage.

Never open the coolant reservoir while the engine is hot, as pressure can cause hot coolant to spray out. Having said that, if the warning light stays on after topping up with the coolant, or if you notice signs like steam, leaks, or rising temperature, it's best not to continue driving in this state and get it checked ASAP.

How often should I change my car’s engine coolant?

The interval for changing engine coolant depends on your vehicle and the type of coolant it uses. For most cars, manufacturers recommend replacing the coolant every 30,000 miles or every 2 years. Some vehicles use long-life or extended-life coolant, which can last up to 60,000 miles or 5 years. Always check your owner’s manual or service schedule for the recommendation specific to your car.

Is it necessary to change the engine coolant?

Absolutely yes — changing your engine coolant is essential. Coolant helps regulate engine temperature, prevents overheating, and protects internal parts from corrosion.

Over time, coolant degrades and becomes contaminated, reducing its ability to cool and protect the engine. Old or dirty coolant can lead to issues like overheating, poor performance, or even engine damage if left unchanged.

Can I change the engine coolant myself?

Yes, you can top up your engine coolant yourself if the level is a little low — just make sure to use the correct type of coolant for your vehicle and only do it when the engine is completely cool.

However, a full coolant change, which involves draining the old fluid, flushing the system, and bleeding out air pockets, is best left to a professional mechanic. It’s easy to get wrong, and mistakes like using the wrong mix or leaving air in the system can lead to overheating or engine damage. So, if your coolant level just needs a top-up, go ahead (safely). But for a proper flush and replacement, it’s safer, cleaner, and more reliable to book in with a pro.

Where do I buy engine coolant from?

You can buy engine coolant from most motor factor shops, car parts retailers, or online. Well-known options include GSF Car Parts, Euro Car Parts or even in supermarkets like Asda, Home Bargains and Tesco.

When buying coolant, make sure to check your vehicle’s handbook or ask a professional to confirm the correct type (e.g. OAT, HOAT, or IAT) and colour for your engine. Using the wrong coolant can reduce protection or cause damage over time.

Can you top up engine coolant with water?

It's not generally recommended. You can top up your engine coolant with water in an emergency, such as when the coolant level is low. This can help you get safely to a garage or home without risking overheating.

Remember, this should only be a temporary solution. Water alone doesn’t offer the same anti-freeze, anti-corrosion, or boil-over protection as proper engine coolant. Over time, using only water can lead to rust, reduced cooling efficiency, and damage to the engine or radiator.

If you've topped it up with water already, make sure to get it drained and refilled with the correct coolant mix as soon as possible.

Which engine coolant should I use for my car?

The type of engine coolant your car needs depends on your vehicle’s make, model, and age. Most modern cars use one of the OAT (Organic Acid Technology), IAT (Inorganic Acid Technology) or HOAT (Hybrid Organic Acid Technology). Your owner's manual will have the exact coolant required for your vehicle. If you're not sure, you can always book a mechanic here to drain and refill the coolant with the right type.

How long should I wait for the engine to cool down before adding coolant?

You should wait at least 30 minutes for your engine to cool down before opening the coolant reservoir or radiator cap. This gives the system enough time to reduce pressure and lower the temperature of the coolant, which can reach over 90°C when the engine is hot.

If you’re unsure whether it’s safe to open the reservoir:
* Check the temperature gauge on your dashboard — it should be at or near the cold mark
* Carefully touch the bonnet or radiator hose (without removing anything) — if it’s still very warm, wait longer

How much does an engine coolant change cost?

The cost of changing your engine coolant typically ranges from £40 to £90, with the average price being around £65. However, the final cost can vary depending on your car’s make and model, as well as the type of coolant recommended by your vehicle’s manufacturer.

What does a ClickMechanic engine coolant change quote cover?

Unless otherwise stated, the quote will cover:

• The cost of the engine coolant
• Coming to you
• The mechanic's labour for replacing the coolant
• VAT (if applicable)
• 12-month parts and labour warranty

Can a mobile mechanic change the engine coolant?

Yes, a mobile mechanic can change your engine coolant as it's a straighforward job. Mobile mechanics are fully equipped to carry out this service at your location, whether it's at home or at work.