How to Check and Add Engine Coolant

Low coolant is a leading cause of overheating. Checking and topping it off takes a few minutes, but doing it at the wrong time can cause serious burns.

The one rule: never open the radiator or coolant cap on a hot engine. Wait until it's completely cool.

What you'll need

• Correct coolant (right type for your car)
• Distilled water (for pre-mix dilution)
• Funnel
• Gloves

Steps

1. Let the engine cool fully

   Park and wait until the engine is cold to the touch — ideally several hours or overnight. Hot coolant is pressurized and can spray and scald.

2. Find the coolant reservoir

   Locate the translucent overflow/expansion tank, marked with MIN and MAX lines. This is where you normally check and add coolant.

3. Check the level

   Look at the level against the MIN/MAX marks while the engine is cold. If it's at or below MIN, it needs topping up.

4. Use the correct coolant

   Match the coolant type specified for your car (color isn't a reliable guide). Use a 50/50 pre-mix, or mix concentrate with distilled water.

5. Add slowly to MAX

   Pour coolant into the reservoir with a funnel up to the MAX line. Don't overfill — it needs room to expand.

6. Check for leaks

   If you're topping up often, you likely have a leak. Look for puddles, white residue, or a sweet smell, and get the cooling system inspected.

Frequently asked questions

Can I just add water?

In an emergency a little water gets you home, but water alone freezes, boils, and corrodes more easily. Refill with the proper coolant mix as soon as you can.

Why is my coolant disappearing?

If you're adding coolant frequently, there's almost certainly a leak — a hose, the radiator, the water pump, or worse, a head gasket. Have it diagnosed promptly to avoid overheating damage.