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Your car's engine generates a lot of heat which, if left unchecked, can cause serious damage. This is why antifreeze is vital to maintaining your car. When mixed with water and added to your radiator, antifreeze helps regulate engine temperature while protecting and lubricating various metal parts in your engine's cooling system.

What is antifreeze and why is it so important to a car?

Antifreeze is a tinted liquid that you put (along with water) in your radiator to help regulate engine temperature. Its key ingredient is ethylene glycol, which lowers water's freezing point and raises its boiling point. This helps prevent the water in your radiator from freezing, boiling, or evaporating.

Along with fuel and oil, antifreeze is essential to a properly functioning engine. Without it, the heat from combustion would cause the engine to rapidly overheat, or even completely seize up. Antifreeze also lubricates cooling system components which come in contact with water, and keeps metal components from corroding.

Are antifreeze and coolant the same thing?

The terms "antifreeze" and "coolant" are often used interchangeably, but this is not correct. Antifreeze is one component of an engine's coolant. It is more accurate to say that coolant is a mixture of antifreeze and water. 

Water alone isn't enough to keep an engine cool. The heat from combustion will eventually cause it to boil over. In the summer, water alone could evaporate away, and in winter, it could freeze, rendering it useless. Most car manufacturers recommend a 50/50 mix of water and antifreeze in your radiator.

Why does antifreeze need to be changed?

Like all fluids in your car, antifreeze deteriorates over time, and eventually becomes more acidic. This causes corrosion, which can damage the radiator and other important cooling system components like the water pump, hoses, thermostat, and the radiator cap.

Rust, dirt, and other harmful particles can also accumulate in your radiator. Contaminants like these will compromise antifreeze's ability to regulate engine temperature. This can lead to the engine overheating, a cracked engine block, or even a piston welding to its cylinder. 

How often should antifreeze be changed, and how do I do it?

Always check your owner's manual first. In general, you should replace your antifreeze every 48,000km (30,000 miles) or every three years, whichever comes first.

When changing antifreeze, allow your radiator and engine to cool for at least an hour. Open the hood and inspect the radiator and hoses for any cracks or leaks. Damaged parts will need to be replaced or repaired. Remove the radiator cap. Loosen the radiator's drain plug and drain the coolant. Tighten the plug, refill the radiator with distilled water, and run the engine for 10 minutes. Allow the engine to cool, and drain once more. Refill the radiator with radiator flush, topping off with more distilled water. Repeat this process until the water runs clear when draining. Finally, fill the radiator with a 50/50 mixture of antifreeze and distilled water, and replace the radiator cap.  

How to put antifreeze in a car?

Make sure your engine and radiator have had at least an hour to cool down. Make a precise 50/50 mixture of antifreeze and distilled water. Carefully remove the radiator cap, add the antifreeze solution, and replace the cap.

Your user's manual is the final authority on procedures like this, so always consult it first. It's also important to remember that your car's coolant system is pressurized and accumulates dangerous amounts of heat. Never perform this task when the engine and radiator are hot. Failure to take the proper safety precautions may result in serious injury.