This blog post clears up the confusion between coolant and antifreeze, explains their roles in your engine, and helps you understand why using the correct fluid is crucial for your car’s health.
Key Takeaways
- Antifreeze is a concentrated fluid (ethylene or propylene glycol) designed to prevent freezing and raise boiling points.
- Coolant is the ready-to-use mixture of antifreeze and water, usually 50/50.
- Radiator coolant, radiator fluid, and engine coolant are all the same thing.
- Using the wrong mixture or type can damage your engine.
- Always follow your vehicle manufacturer’s guidance when choosing coolant.
The Core Distinction – Antifreeze is an Ingredient
Antifreeze Defined:
Antifreeze is a concentrated chemical solution, usually made from ethylene glycol or propylene glycol. Its main job is to lower the freezing point of water while raising its boiling point, protecting your engine in extreme temperatures. However, antifreeze on its own is not ready for use—pouring pure antifreeze into your cooling system could actually harm your engine.
Coolant Defined:
Coolant is what your car actually uses. It’s a pre-mixed solution of antifreeze and distilled or deionised water, with a standard 50/50 ratio. This balanced mix:
- Prevents both overheating and freezing.
- Flows effectively through the cooling system to regulate engine temperature.
- Protects metal components from corrosion.
Common Misconceptions:
- Is radiator coolant the same as antifreeze? No. Antifreeze is the concentrate; coolant is the final mixture.
- Is engine coolant the same as radiator fluid? Yes. These terms all refer to the same pre-mixed liquid your car needs.
Why the Distinction Matters – The Role of the Cooling System
Why not just use water? Your engine runs at high temperatures, and plain water would fail under stress. Here’s why the coolant/antifreeze blend matters:
- Prevents Freezing: Water expands as it freezes, which could crack your engine block. Antifreeze keeps the fluid liquid even in sub-zero conditions.
- Prevents Overheating: It raises the boiling point of water, stopping it from evaporating into steam and leaving your engine vulnerable.
- Corrosion Protection: Modern antifreeze formulas include additives to prevent rust and corrosion inside your radiator, hoses, and engine components.
For more, see the RAC’s guide to antifreeze and coolant.
Common Misconceptions & When to Use What
Myth | Truth |
“I should just use pure antifreeze for better protection.” | False. Pure antifreeze doesn’t transfer heat well and can cause overheating. Stick to 50/50. |
“It’s fine to top off with just water.” | False. A little in an emergency is okay, but long-term use dilutes protection against freezing, overheating, and corrosion. |
“All coolant is the same.” | False. Different types exist (OAT, HOAT, IAT), and using the wrong one can damage seals and gaskets. |
When to Use Which:
- Pre-mixed Coolant (50/50): The safest, most convenient choice for most car owners. Perfect for topping up or refilling.
- Concentrated Antifreeze: Best left to professionals or specific situations (e.g., extreme climates needing a 60/40 mix).
A Quick Guide to Choosing the Right Coolant
The best coolant depends on your car manufacturer’s specifications—never guess.
How to Find the Right Type:
- Check your owner’s manual. This is the most accurate guide.
- Look under the bonnet. Some cars have a label near the radiator cap or expansion tank that specifies the coolant type.
- Ask an expert. If in doubt, APD’s knowledgeable team can help.
For extra clarity, see the AA’s coolant and antifreeze advice.
Shopping for Antifreeze and Coolant
To recap:
- Antifreeze is the concentrate.
- Coolant is the pre-mixed solution.
- The 50/50 mix is essential for regulating your engine’s temperature and protecting against corrosion.
Ready to top up or replace your coolant? Check out APD’s full range of coolant and antifreeze products.