How to Check and Add Coolant (Antifreeze)

Difficulty: Beginner Time: 5–10 minutes (plus cool-down time)

Coolant, also called antifreeze, carries heat away from the engine. If it gets low, the engine can overheat, which can cause very expensive damage.

Checking it takes a couple of minutes, but there is one rule you must never break: do not open the radiator cap or coolant reservoir cap while the engine is hot. The system is under pressure, and hot coolant can spray out and cause serious burns.

What you'll need

Step by step

1. 1

   Let the engine cool completely

   Park on level ground and wait until the engine is cool to the touch, preferably a few hours or first thing in the morning.

2. 2

   Find the coolant reservoir

   Open the hood and look for a see-through plastic tank, usually near the radiator, with a cap marked with a coolant or warning symbol and MIN/MAX (or LOW/FULL) lines.

3. 3

   Check the level

   Look at the side of the tank. The coolant should be between the MIN and MAX lines when the engine is cold. Use a flashlight if it is hard to see.

4. 4

   Check the color

   Coolant is usually green, orange, pink, yellow or blue. If it looks rusty brown, oily or sludgy, the system needs a professional check, not just a top-off.

5. 5

   Open the reservoir cap slowly

   With the engine cold, cover the cap with a rag and turn it slowly to release any pressure, then remove it.

6. 6

   Add coolant to the MAX line

   Using a funnel, pour in the correct coolant until the level reaches the MAX (or FULL COLD) line. Do not overfill.

7. 7

   Close the cap and clean up

   Tighten the cap until it clicks or is snug, wipe up any spills, and put the jug away out of reach of children and pets.

8. 8

   Check again after driving

   Check the level again the next morning. If it has dropped, there is probably a leak.

Tips

• Use the coolant type listed in your owner’s manual. Mixing types can cause problems. Pre-mixed 50/50 coolant is ready to pour.
• In an emergency, plain water can get you to a shop, but it should be replaced with proper coolant soon.
• Look under the car for drips. Coolant puddles are often bright colored and smell sweet.

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Frequently asked questions

Can I add coolant when the engine is hot?

No. Never open the radiator or reservoir cap on a hot engine. The coolant is under pressure and can spray out and burn you. Wait until the engine has cooled completely.

What kind of coolant does my car need?

Check your owner’s manual or the reservoir cap. Cars use different coolant types, and using the right one protects the engine. Pre-mixed 50/50 is the easiest to use.

Can I use water instead of coolant?

In an emergency, water can get you to safety, but it does not protect against freezing or corrosion. Replace it with the correct coolant soon.

Why does my coolant keep getting low?

Coolant does not get used up like gas, so a dropping level usually means a leak: a hose, the radiator, the water pump, or sometimes a head gasket. Have it inspected.

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