Refilling the fluid antifreeze or coolant is something you should only do when the engine is cool. Don't attempt to handle this right after the vehicle has been driven. Coolant systems are pressurized, which means the reservoir is very dangerous to open while it's hot. Just wait until the engine is cool.

How often do you need to refill coolant?

A typical mechanic will recommend changing coolant every 30,000 miles. But many will tell you, changing the coolant is not even on their radar. An owner's manual might recommend changing the coolant/antifreeze after the first 60,000 miles, then every 30,000 miles.

How do you know when to add coolant?

Rather than open the cap on the radiator, just check to see whether the liquid reaches the “Full” line on the side of the coolant reservoir shown here. It's part of the coolant recovery system. If the liquid doesn't reach the “Full” line, open the bottle and add a 50/50 mix of water and coolant until it does.