Types of Coolant for Cars
Coolant, also known as antifreeze, is a vital fluid for the proper functioning of the engine. Its main function is to regulate temperature, preventing the engine from overheating in summer or the cooling system water from freezing in winter. In addition, it protects metal parts against corrosion and the buildup of deposits.
Although it may look like a brightly colored liquid, each type of coolant has a different chemical composition and they should not be mixed with one another.
1. Inorganic Coolant (IAT – Inorganic Acid Technology)
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Common color: green
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Characteristics: contains silicate- and phosphate-based additives that protect metal surfaces
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Lifespan: about 2–3 years (approx. 40,000 km)
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Recommended use: older cars (generally manufactured before 2000) with copper or brass radiators
2. Organic Coolant (OAT – Organic Acid Technology)
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Common colors: orange, red, pink, or blue (depending on the manufacturer)
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Characteristics: uses organic additives that directly protect metal parts, especially aluminum
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Lifespan: 5–7 years (up to 150,000 km)
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Recommended use: modern vehicles with aluminum engines and closed systems
3. Hybrid Coolant (HOAT – Hybrid Organic Acid Technology)
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Common colors: yellow, turquoise, or even purple
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Characteristics: combines inorganic and organic additives, offering corrosion protection and longer durability
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Lifespan: about 5 years or more, depending on the manufacturer
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Recommended use: European vehicles and some modern Asian/American cars
4. Phosphate Hybrid Coolant (P-HOAT)
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Common colors: blue or pink
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Characteristics: includes phosphates that improve protection in humid climates
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Recommended use: Asian vehicles (mainly Japanese and Korean)
5. Silicate Hybrid Coolant (Si-HOAT)
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Common colors: purple or violet
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Characteristics: contains silicates and organic acids, making it highly effective at protecting aluminum and magnesium
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Recommended use: European cars (Mercedes-Benz, BMW, Audi, VW)
Importance of Colors
The color of coolant is not universal:
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It serves as a quick reference to differentiate types, but not all manufacturers follow the same code
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Two coolants of the same color may have different compositions
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The most important thing is to check your car manufacturer’s manual and use the recommended type
Practical Tips
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Never mix different types of coolant, as it can reduce effectiveness and damage the cooling system
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Regularly check the coolant level and condition (if it loses color or looks brown, it should be replaced)
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Always use coolant, not just water, since water alone does not protect against corrosion or regulate temperature properly
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Replace coolant according to the manufacturer’s recommendations, not only by mileage but also by time
