Antifreeze Vs Coolant – What is the Difference Between Them?

When it comes to antifreeze and coolant, you’ve probably heard these two terms used interchangeably, right?

Perhaps you’ve come to think of them like the automotive equivalent of soda and pop, two different words used to describe the same substance?

Or maybe you believe they are different substances, and you’re looking to confirm your opinion?

In this article, we’re going to answer all the questions you may have concerning antifreeze vs. coolant.

Gloved hands puring antifreeze into a car engine

Below, you’re going to learn what distinguishes coolant from antifreeze and if they are indeed the same thing. You’ll also become familiar with the ingredients these products are made of.

You’ll learn what antifreeze looks like and the purpose it serves in your car. We’ve also detailed what all the different colors of antifreeze signify and what makes them unique.

Finally, we cover how to check if your car has enough of it, this being one of the most basic yet important maintenance tasks you have to take care of with your vehicles.

What is Antifreeze?

Antifreeze is an essential part of your car’s cooling system. It works to regulate the temperature inside your engine as it runs.

The majority of brands consist of one of two active ingredients. This can include either ethylene or propylene glycol.

Most, if not all, products will also contain additives, and some are pre-mixed with distilled water, (though coolant is never water alone!)

So what are ethylene and propylene glycol?

Ethylene Glycol

This is a form of alcohol that is naturally odorless and colorless. It has a freezing point of 8.6 degrees Fahrenheit and a boiling point of 388 degrees Fahrenheit.

When mixed with water, it can increase the liquid’s boiling and freezing points. It isn’t harmful to metal components and doesn’t degrade quickly.

All of these qualities make it useful for use in coolant systems. Unfortunately, though, ethylene glycol is highly toxic.

Two ounces could be fatal to the average adult. It also has a sweet taste, which could entice children, pets, and wildlife to drink it.

Propylene Glycol

Propylene glycol is colorless, odorless, and tasteless. It’s a synthetic liquid that has many industrial applications. For instance, it’s used to manufacture certain polyester compounds.

This syrupy fluid isn’t as hazardous as ethylene glycol. It’s usually advertised as a non-toxic alternative to ethylene glycol.

It also has a higher boiling and freezing point. These are 370 degrees Fahrenheit and -74 degrees Fahrenheit, respectively.

Still, this doesn’t mean it should be consumed or misused. It must be kept out of reach of pets and children.

Helpful Additives

Additives are compounds added to a product to improve how it works. They can be found in motor lubricants, paints, fuel stabilizers, and more.

In antifreeze, additives play several roles. For example, they can inhibit corrosion to protect your car’s inner workings, or delay the inevitable breakdown of the fluid, extending it’s lifespan and time between top-ups or changing. Antioxidant-based additives help to clear debris that builds up in the coolant system.

These are just a few examples. Basically, additives enhance how antifreeze works, improving its usefulness.

What is Coolant?

Coolant is typically a mix of distilled water and antifreeze. The ideal ratio is half and half, although this can change based on your car’s needs.

You may need a higher ratio of antifreeze to water if you have brutal winters. This will prevent the water from freezing in the bitter cold.

It isn’t advisable to use exclusively water-based coolant. This is because water is not as adept at regulating temperature as ethylene and propylene glycol.

Plus, water doesn’t have any additives in it. This fluid alone can’t offer any protection or benefits to your vehicle’s internal components.

Is Coolant the Same as Antifreeze?

For most intents and purposes, the answer is yes. Referring to them interchangeably isn’t like confusing diesel with gasoline.

You could say that antifreeze is an ingredient of a coolant mixture when it’s mixed with water, either distilled or tap water. However, this is only if you want to be extremely specific.

The two are more or less the same thing. However, the brands, types, and mixtures will vary from brand to brand, and which to use will vary from car to car.

What Does Antifreeze Look Like?

All the best antifreeze manufacturers use dye. Remember that both ethylene and propylene glycol are naturally colorless. Vivid dyes enable us to spot if there’s a leak, so it’s also easier to ensure accidental spills are thoroughly cleaned up and any antifreeze is disposed of correctly.

You can buy one of three types. Your options are inorganic acid technology (IAT), organic acid technology (OAT), and hybrid organic acid technology (HOAT).

Green (OAT)

Most green brands are made with inorganic acid technology (IAT). They’re rich in silicates to prevent vulnerable metals from rusting.

The green types are best for cars manufactured no later than 1990. The silicates are beneficial for radiators made of copper, aluminum, and brass.

Pink, Orange, Dark Green (IAT)

These colors tend to represent organic acid technology brands (OAT). They can come in a rainbow of colors except for neon or light green.

This is to prevent them from being mistaken with traditional IAT products at first glance. OAT antifreeze doesn’t contain silicates.

Instead, it’s packed with additives to improve performance. Common varieties include corrosion inhibitors and other compounds to extend lifespan.

Yellow and Orange (HOAT)

Hybrid organic acid technology (HOAT) is a mix of OAT and IAT antifreeze. These brands are made with silicates but are also formulated with additives.

HOAT brands are often found in major automotive brands. For example, manufacturers like Mercedes Benz or Chrysler.

What Does Antifreeze do?

There are a couple of things antifreeze does, most importantly it regulates temperature and shields metal engine components from rust.

If you want to know how the whole system works, watch this video.


Dissipates Heat

The engines in our vehicles run hot. Average operating temperatures can range from 195 to 220 degrees Fahrenheit.

The coolant fluid helps dissipate heat. In turn, this reduces heat-based wear on engine components.

Prevents Freezing

The name says it all, it stops your engine from freezing solid. As we’ve established, propylene and ethylene glycol have low freezing points.

Reduces Corrosion and Prevents Sediment Build-Up

The additives in coolant protect metal pipes and mechanisms from corrosion.

Certain brands also contain additives to break down debris and sediment buildup that can cause rust over time.

How to Check Your Car’s Antifreeze/Coolant Levels

Want to make sure your car isn’t in need of a refill? Check the coolant or antifreeze levels by following our simple guidelines.

We’ve provided instructions for both older and newer cars.

Newer Vehicles (Coolant Reservoir)

Here’s how to inspect your coolant reservoir to see if it’s full:

  • Step 1 – Park your car and pop open the hood. If you were running the engine, give it at least 30 to 45 minutes to cool off.
  • Step 2 – Locate the coolant reservoir—this will depend on the make and model of your car. Check your vehicle’s manual to find out where it is.
  • Step 3 – There should be a fill line marked on the side of the reservoir. If the fluid isn’t at the “full” line, you can top it off.

Older Vehicles (Radiator)

Older automobiles may not have a coolant reservoir. Follow these simple steps:

  • Step 1 – Get your car parked conveniently to check under the hood. Allow the engine 30 to 45 minutes to cool down if you were driving.
  • Step 2 – Find your vehicle’s radiator. If you’re not sure where to look, check your car’s manual.
  • Step 3 – Unscrew the pressure cap and take a peek inside. If you can see the fluid, you’re fine. If not, you’re going to have to add more.

Don’t forget to put the cap back on your radiator before you close the hood.

Final Thoughts

The next time you find yourself in a discussion on the difference between coolant and antifreeze, you should now be prepared and able to clear up any misconceptions your friends or family may have.

Do you have any questions or feedback you think we should hear? Please do tell us in the comments below, we’ll make sure to get back to every one of you!

From childhood go karting and motocross, to collecting and obsessing over scalextric, matchbox and radio controlled cars, I've always had an obsession with cars. Learning through manuals, books, trial and error, and more knowledgeable family members, I've also enjoyed tinkering with the mechanics and electronics of any vehicles I've owned. Now, over 3 decades later, I've started this site as a place for me to share my knowledge, to teach others how to care for and maintain their vehicles themselves, at home, so they can get the most of their vehicles and save a pretty penny compared to always seeking out professional help.

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