Why the interval varies
Coolant does more than stop freezing: it carries additives that protect the engine and radiator from corrosion. Those additives wear out over time. Long-life coolants last much longer than older formulas, which is why intervals range from a few years to a decade.
Use the type your manual specifies. Coolants are not all compatible, and mixing types can reduce protection.
Checking coolant safely
Never open the radiator cap on a hot engine. The system is under pressure and the coolant can be scalding. Check when the engine is cold.
Look at the see-through overflow reservoir: the level should sit between the marks. A level that keeps dropping means a leak somewhere, even if you can’t see a puddle.
Warning signs
- The temperature gauge running higher than normal, or an overheating warning — pull over safely and turn the engine off
- A sweet smell, or green, orange or pink fluid under the car
- Steam from under the hood
- Poor heater output in winter
- Coolant that looks rusty, muddy or has debris in it
Common questions
Can I just top it up with water?
In an emergency, water can get you somewhere safe, but it dilutes freezing and corrosion protection. Top up with the correct coolant mix as soon as you can.
Is a coolant flush the same as a coolant change?
Both replace old coolant; a flush also pushes cleaner through the system. Follow the procedure your manufacturer specifies.