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Let’s Talk Radiator Fluid: Engine Coolant Vs. Antifreeze

Key Takeaways:

  • Antifreeze is a liquid concentrate based on ethylene glycol
  • Engine coolant is antifreeze mixed in distilled water
  • Antifreeze works well for both summer & winter to stablize car engine temperatures.
  • Engine coolant helps keep the car’s engine temperature regulated.
  • Depending on mileage, the fluid needs changing every 30,000 miles or 2 years.

Your car's radiator is an essential part of the cooling system. It helps keep your engine from overheating, and it's essential to use a suitable radiator fluid to ensure that your car keeps your car cool and running smoothly.

There are two types of this fabulous fluid: engine coolant and antifreeze. So, what's the difference between them? Let's take a closer look.

What Is Antifreeze?

An ethylene glycol-based liquid, antifreeze lowers the freezing point of radiator fluid and raises its boiling point. To put it simply, antifreeze works to stabilize your car's engine during the winters and keep your car cool during the summer. It also features corrosion inhibitors to keep your radiator hoses and engine clean.

In a nutshell, this liquid is vital to the overall health of your engine and radiator. Its concentrate form is usually green, red, or yellow.

If your coolant antifreeze is beginning to lose efficacy, you may need to read up on the signs of a faulty radiator!

What Is Engine Coolant?

On the other hand, engine coolant is a mixture of water and antifreeze. It's crucial to remember that you should never use water alone as a coolant fluid. That's because water boils at a lower temperature than antifreeze, which means it would vaporize too quickly in your radiator.

The boiling point of engine coolant is far higher than that of water, which means it can better withstand the heat produced by your engine. It also does a better job of regulating the temperature in your radiator, keeping it from overheating.

Engine coolant serves the same purpose as antifreeze, working to weather your car through freezing temperatures and keep your car cool in the summer. But there are a few notable differences between engine coolant and antifreeze that you should be aware of.

What's the Difference?

Antifreeze can’t be used alone in a car’s engine because itself it happens to be a poor conductor of heat. Your car would last 2-5 minutes before it just seizes. However, the fluid can keep engine coolant liquid at temperatures as low as -35 degrees Fahrenheit, which fulfills its purpose.

If there is less antifreeze, or none at all in the coolant, and only water is used, the fluid freezes. Build of stresses can result in damage to the hoses inside the engine block that allow coolant through. That's why engine coolant is the radiator fluid of choice in areas with frigid winters.

But here's where it gets tricky: not all engine coolants are created equal. Some mixtures come in half-half ratios, while others feature a 30/70 split of water and antifreeze. The right mix for your car depends on the climate you live in and the radiator fluid's boiling point.

Which Is Better?

With mild winters in Monterey Park, CA, a 50/50 mix of radiator fluid should do the trick in most cases. This mixture will have a lower freezing point than pure water and a higher boiling point than pure antifreeze. That said, it's always best to grab your owner's manual and see the coolant recommendations for your specific vehicle.

Summers in California are hot, so you'll need a fluid mixture to stabilize your car’s core temp and keep it cool. While 100% antifreeze will have a higher boiling point, it will damage the engine – it is just impractical to use that way. A 70/30 fluid mix is recommended for most vehicles during the summer.

The added water will also help to lubricate the water pump and reduce the overall engine temperature.

When Should I Change the Fluid?

Your engine coolant or antifreeze should be flushed and replaced every 30,000 to 50,000 miles. If you're questioning the last time you changed your car's coolant, it's always best to stay safe and have it done sooner rather than later.

That said, there are several signs that it's time to change this fabulous fluid. Let's run through them:

  1. The temperature gauge: If you catch your temperature gauge reading higher than usual, it might be time for a fluid flush.
  2. Leaks and puddles: You can usually find fluid leaks around the radiator hoses, the radiator cap, and the water pump. If you see any greenish-yellow puddles under your car, it's time to give us a call.
  3. A grinding noise: As your engine coolant or antifreeze deteriorates, it can start to eat away at radiator hoses and gaskets. This usually results in a grinding noise coming from under the hood.
  4. Rust: You might discover rust in your coolant fluid if you let it go too long without a change. If you notice any rust, bring your vehicle in as soon as possible.
  5. Steam and smells: Fluid that's boiling or radiator hoses that are hot to the touch are signs that your coolant needs rapid replacement. You might also notice a sweet smell under the hood - this is usually a sign of coolant leaks.

What Are the Causes of Coolant Leaks?

Now that we've discussed signs that it might be time for a fluid flush let's talk about some of the causes of coolant leaks.

  1. Faulty radiator cap: The cap is responsible for maintaining proper pressure in the cooling system. If it's not functioning correctly, it can induce coolant leaks.
  2. Cracks in the radiator: Over time, radiator hoses can develop cracks. These require repairs as soon as possible to prevent coolant leaks.
  3. Water pump failure: This pump circulates coolant through the engine. If it fails, it can cause coolant to leak.
  4. Defective expansion tank: The expansion tank stores coolant that has expanded due to heat. If it becomes defective, it can cause coolant to leak.
  5. Blown head gasket: The head gasket seals the engine block and the cylinder head. It also keeps the engine oil and coolant from mixing. If it blows, it can cause coolant to leak.

Can I Put Antifreeze or Coolant in Oil?

Your car's engine oil and coolant serve different purposes, so it's important not to mix them. Coolant or antifreeze cools your engine while the oil lubricates engine parts. Mixing your coolant fluid and oil can cause severe damage to your engine.

Don't start the engine if you accidentally mix the coolant with your car's oil. This will cause the coolant fluid and oil to circulate through your engine, damaging it beyond repair. Instead, call a tow truck and take your car to a nearby service station or dealership for repairs.


That was our quick guide to antifreeze and engine coolant. Now you know the difference between these fabulous fluids, and you can keep your car running smoothly throughout winter. Nissan cars hold impressive performance records, and the engine coolant is one of the main reasons behind them.

If you'd like to know more about Nissan car performance, or more about some of the best performance cars in the world, check out our Nissan inventory at Glendale Nissan, serving Monterey Park, CA.

Thanks for reading & schedule a service with us today!


Let's Talk Radiator Fluid: Engine Coolant Vs. Antifreeze - Glendale Nissan

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