Most modern cars have a translucent plastic overflow tank that holds extra coolant, and it is attached to the radiator with a hose or tube. Simply check to see that the level is up to the mark.

If you need to add coolant, use a mixture of half water and half antifreeze. If you don’t have an overflow tank, you’ll need to remove the radiator cap itself. The coolant level should be within a couple of inches of the top.

Don’t remove the cap from a hot radiator. Wait at least 20 minutes for the engine to cool down, and always cover the cap with a rag as you remove it, to avoid hot water coming into contact with your skin..