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Antifreeze vs Coolant: What’s the Difference? (Explained)

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Antifreeze and coolant are used in the cooling system of a vehicle and are essential for regulating engine temperature. But what’s the difference between them?

Antifreeze is usually made up of pure ethyl glycol whereas coolant is the mixture of distilled water and antifreeze. Coolant is essentially pre-mixed and can be added directly into the cooling system.

In this article, we’ll discuss the differences of coolant vs antifreeze and understand what they do.

a coolant reservoir in a car

What Is Antifreeze?

Antifreeze is a liquid used in a vehicle’s coolant system to stop the water from turning to ice in colder climates.

Typically, it’s composed of ethylene glycol, a colorless and odorless liquid. Be careful when handling antifreeze as it can be harmful to both humans and animals.

Antifreeze also increases the boiling point of water, facilitating the engine’s ability to function at elevated temperatures without the coolant boiling.

It also lowers the freezing point of water, helping to avoid freezing of the coolant within the engine.

What Is Coolant?

Coolant, which is a blend of antifreeze and distilled water, is introduced to the engine to manage its temperature effectively.

Two ratios of water to antifreeze are widely used: a 50/50 mix and a 70/30 mix.

  • The 50/50 mix, composed of equal parts of antifreeze and water, is appropriate for most weather conditions and climates.
  • The 70/30 mix, comprising 70% antifreeze and 30% water, is better suited for extremely cold climates.
  • In warmer countries, the proportion of water to antifreeze could be considerably higher, or they may even use 100% distilled water, given that the risk of the vehicle’s engine coolant freezing is minimal.

Coolant is usually pre-mixed and can be poured directly into the cooling system, it sometimes has other additives included which is why you should always use the right coolant for your vehicle.

Their Differences

The fundamental difference between antifreeze vs coolant lies in their composition; antifreeze is a single, pure chemical compound, while coolant is a blend of antifreeze and water, and sometimes other additives.

  • Antifreeze is incorporated into the coolant system to stop the water from turning into ice and also raises the coolant’s boiling point.
  • Engine coolant, a combination of antifreeze and water, is introduced into the engine with the purpose of regulating its temperature via the cooling system (such as the radiator, thermostat, etc).

Can I Add Only Antifreeze to My Car?

While it’s possible to add antifreeze to your vehicle’s cooling system, it’s generally not advisable to do so if the system is already filled with coolant.

Rather, it’s recommended to use a pre-formulated coolant, a mix of antifreeze and water.

Always remember to refer to your vehicle’s owner’s manual or seek advice from a mechanic for specific recommendations pertaining to your car.


Selecting the appropriate antifreeze and engine coolant for your vehicle is vital to ensuring the longevity of the engine.

Knowing the difference between antifreeze and coolant, as well as determining the correct ratio of antifreeze to distilled water suitable for your climate, is important.

Always refer to your vehicle’s owner’s manual or seek advice from a professional mechanic for particular suggestions relevant to your car.

  • Andy Lewin

    Andy Lewin is a senior mechanic, ASE qualified master technician, and an experienced automotive engineer.He's passionate about serving the automotive community with the highest-quality and trustworthy information on all things automotive. He loves to write about car repairs, maintenance, car modifications and tuning, faults, and much more.

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