Checking coolant — when and why

What does coolant actually do?

Coolant — also called antifreeze — is not plain water. It's a mixture that does three jobs at once: it cools your engine by carrying heat away, it protects against freezing in winter and boiling in summer, and it prevents corrosion in the cooling system and the engine.

That corrosion protection is what sets it apart from water: pure water would rust your radiator, water pump and engine block from the inside. The additives in coolant stop that — but those additives wear out over time. That's why coolant isn't something you 'pour in once and forget': both the level and the quality need to be kept up.

When to check and when to replace?

Check the level on a cold engine — never on a warm one, because the system is under pressure and you can scald yourself. Look whether the level in the expansion tank sits between the min and max marks. Does the level keep dropping after you top up? Then coolant is leaking somewhere and you should have it checked.

• Checking the level: regularly yourself and as standard at every service with us — always on a cold engine.
• Replacing: to the manufacturer's spec. For many cars that's around every few years or ~60,000–100,000 km, but it varies by make and type of coolant.
• Never just add water — that dilutes the protection; use the right coolant for your car.

Not sure what applies to your car? Enter your license plate and we'll look up the manufacturer's spec.

Warning signs you should take seriously

Coolant usually lets you know before things really go wrong. Recognise one of these signs? Have your car checked:

• Temperature gauge climbing — the needle creeps towards red or the engine gets noticeably hot.
• Low-coolant warning light — a low-level or temperature message on your dashboard.
• Sweet smell — coolant smells sweetish; if you notice it in or around the car, something is probably leaking.
• White steam from the engine bay or the exhaust.
• Puddle under the car — a coloured (often pink, green or orange) patch on the ground.
• Heater blows cold — the cabin heater uses the heat from the coolant; if it stays cold, the level may be too low.

Why you shouldn't ignore this

A shortage of coolant, or worn-out coolant, leads to overheating, and overheating is one of the most expensive things that can happen to your engine. An engine that runs too hot can warp the cylinder head or blow the head gasket — and that's a big, expensive repair, sometimes engine damage.

The tricky part is that it can happen quickly: once the temperature gauge is in the red, the damage is already adding up. So don't keep driving with a warning on your dashboard. Checking, topping up and replacing to spec in time costs a fraction of what an overheated engine costs — and keeps you from being stranded by the roadside.

How AutoJet helps: free check, replaced by license plate

At AutoJet in Almere we check your coolant as standard at every service — we look at the level and the quality and tell you honestly what's going on. Suspect a leak? Then we run a pressure test on the cooling system to find where it's leaking.

If topping up or replacing is needed, we use the right coolant to the manufacturer's spec for your car. The coolant check is included in a service — a small service costs €170 and a large service €320. Enter your license plate and you'll see the price up front. We speak Ukrainian, Russian and English — handy if Dutch isn't your first language.

The final price depends on your car — enter your license plate and you'll see it up front. You never pay for work you haven't approved in advance.

See also: Maintenance in Almere · Blog

Frequently asked questions about checking coolant