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Antifreeze — What's So Hot About the Coolest Car Fluid?
It keeps your car from freezing in the winter and keeps it cool in the summer? What is antifreeze, anyway — a magical potion? Not exactly, but it may feel like it at times. When the engine roars to life on a -14 °F morning in Colorado, you certainly feel a sense of wonder and delight!
We’re decoding antifreeze to help drivers better understand its importance in a vehicle’s engine. Read on to explore answers to some of our customers’ most common questions — how it works, why you need it and the consequences of forgetting it. We also tackle the importance of antifreeze safety and storage. Let’s break down some cool facts on this hot topic!
What Does Antifreeze Do?
Antifreeze is an essential fluid in your vehicle’s cooling/radiator system. The chemical name for the specific antifreeze used in car/truck engines is ethylene glycol. Ethylene glycol is a synthetic chemical that has unique properties: When you combine it with water to create coolant, it increases the boiling point of the entire solution. It also lowers the freezing point.
You will often hear the words “antifreeze” and “coolant” used interchangeably when talking about your radiator system. It doesn’t hurt to talk about them either way, but the ultimate difference is that antifreeze is concentrated ethylene glycol. Coolant is the solution created when you combine ethylene glycol with water.
Engine coolant’s dual capability is critical for your engine, which relies on water absorbing heat and moving through a pressurized system to control high temperatures and prevent damage (see diagram).
At the same time, vehicles in colder climates like Colorado can prevent an additional concern — the system freezing in winter weather. Remember, water is necessary to cool the engine, but on its own it’s vulnerable to freezing when temperatures plummet. Water expands when it freezes and your coolant system is a closed loop. There’s nowhere for it to go but out, and out is expensive.
There’s a third reason antifreeze is beneficial — the manufacturer additives that protect your radiator system. Antifreeze may include anti-corrosion properties, defoaming agents, PH correctors and even a bittering agent that makes it less sweet. (You can read more about the importance of antifreeze safety below.)
Other Familiar Names for Antifreeze
- Coolant
- Ethylene glycol
- Radiator fluid
- De-icer (depending on where you live)
- Engine coolant
Why Do You Add Water to Antifreeze? Why Not Just Use Straight Antifreeze?
Water and ethylene glycol are quite the dynamic duo because they are stronger together — hence the reason you need both in your system. It’s so important to use them together that many manufacturers sell pre-blended engine coolant solutions to make it easier for people to refill their cars between maintenance appointments.
Without water, ethylene glycol freezes at around 10.4°F. Yes, antifreeze will freeze on its own. Water freezes at 32°F. Together, however, they withstand temps much lower than they ever could alone. The science of it is pretty, well, cool. Or is it hot? Whatever it is, it’s not freezing! Ethylene glycol molecules mix amongst the water molecules, preventing them from forming the hydrogen bonds that crystalize water into ice. Some solutions can withstand temperatures as low as -67°F!
That’s a lot of conversation about freezing points for a solution that’s also called a “coolant,” right? Let’s talk about that. Remember, just as ethylene glycol lowers the freezing point of water, it also increases the boiling point. And, that’s really the point of coolant, despite how much we appreciate the anti-freeze properties in colder climates like the Colorado Rockies.
The boiling point of water at sea level is 212°F. Ethylene glycol has a much higher boiling point, but lower heat capacity, making it a poor option on its own. Combining the two 50/50 in a pressurized system increases the boiling point of the solution to 265°F. This creates optimal conditions for engine performance because the average vehicle engine has an operating temperature of 195°F-220°F. (With the proper coolant solution and a working radiator system.)
And those additives we mentioned above? Well, it turns out that you need water to uniformly suspend them in your system. In straight ethylene glycol, the additives sink and can create the corrosion they were intended to prevent. Water is the solvent that carries the additives as the engine coolant flows through the system.
What Happens Without Coolant?
Your radiator system, powered by water and coolant, is the only thing stopping the heat of powering the engine from destroying that engine. Here are some potential problems that can occur if you don’t maintain your coolant:
Car overheats: You may notice the temperature light come on or notice the temperature dial climbing as you are driving. If your car overheats:
- Pull over and turn the car off.
- Caution: Wait at least 30 minutes before dealing with an overheated car. It can be very dangerous! Remember, your radiator is a pressurized system and your vehicle is already overheated. Do not touch the radiator cap or open the radiator. Do not touch or open the coolant reservoir for the first 30 minutes.
- Once the car has cooled, check the coolant reservoir. If it is empty, add more coolant.
- Turn on the car and wait for the system to cycle through the added coolant. Proceed, monitoring the temperature.
- Note: Some guides may recommend you add coolant directly to the radiator. Do not open the radiator cap unless the car is completely cooled and you are experienced with cars and the dangers of radiators in particular.
- If the reservoir is full, schedule an appointment for an inspection. There may be deeper problems with your vehicle.
Car shuts down: Newer cars may turn the car off when a certain temperature triggers the fail-safe. You should not rely on that if you see the gauge suddenly climbing.
Serious engine damage: If you drive your car while it is overheating, you’re gambling on a potentially costly repair bill. That’s also true if you live in a climate with freezing temps and you don’t add a properly mixed coolant. Antifreeze is one of the core essential fluids for your vehicle for a reason!
- Engine seizing
- Warped cylinders
- Busted water pump
- Cracked engine block
- Frozen hoses
- Radiator damage
- Leaking hoses
- Cracked cylinder heads
Does Antifreeze Color Matter?
Antifreeze colors are not exactly standardized, but color can signal that a product has a particular additive or is used for a specific vehicle type. Consult your owner’s manual or discuss what you need for top-ups with your mechanic during your next service appointment to get the best answer. The chart below has general information about antifreeze color.
Antifreeze Color Chart
🟩 GREEN | This is the classic color we all associate with antifreeze and signals a version containing Inorganic Acid Technology (IAT). |
🟧 ORANGE | The grandchild of classic green, orange antifreeze is longer lasting and fairly standard in most vehicles today. It contains Organic Acid Technology (OAT). |
▩PINK⬚⬚⬚⬚⬚⬚ | Pink signals an antifreeze containing Phosphate-based hybrid/non-hybrid organic acid tech (P-HOAT, POAT). |
🟥 RED | Like orange antifreeze, red uses OATs. Used in diesel engines and some foreign cars (Asian/European). |
🟦 BLUE | Blue antifreeze should only be used with specific vehicles. It uses phosphate-free technology, both hybrid and non-hybrid (P-OAT, HOAT). |
🟪 PURPLE | Purple’s distinction is its common use in Stellantis vehicles like Jeep, Dodge and Chrysler. |
Please remember to consult your mechanic or review your owner’s manual before adding antifreeze to your vehicle.
Does Antifreeze Expire?
Antifreeze lasts about three to five years in your vehicle or 30,000+ miles. However, there are several factors that can influence how often you should flush your system. For example, if your antifreeze relies on specific additives, those can lose effectiveness over time. Old radiator fluid can also acidize and corrode your cooling system. You can check your owner’s manual or give us a call if you want to learn more about a coolant fluid exchange whether or not you need one.
What Are the Dangers of Antifreeze/Coolant?
Antifreeze — ethylene glycol — is poisonous to humans and animals. It is naturally sweet, and even though many manufacturers now include bittering additives to deter ingestion, you should always proceed with extreme caution with storage, disposal and leaks. A small puddle under the car could endanger wildlife, curious kiddos and pets.
Watch out for:
- Spills, drips and soaked rags
- Antifreeze leaks under or around vehicles
- Older/abandoned bottles of coolant
- Leftover antifreeze in non-working vehicles
- Leaking disposal containers/industrial containers
It is important to remember that even with the newer bittering agents, this is a harmful fluid that can cause a painful death. Never count on the taste to discourage potential poisoning.
- Keep the bottle lid sealed and “locked” tight — always. Don’t leave caps loose for easy access or quick use.
- Keep bottles out of reach of children.
- Do not discard fluid in the trash, drains, sink or local dump. Use the local disposal facility in El Paso County:
- El Paso County Household Hazardous Waste Facility: 3255 Akers Dr., Colorado Springs, 80922 | 719-520-7878 | evs-epc@elpasoco.com
- Use a mechanic for radiator flushes or anything that requires you to replace the coolant in larger amounts. Honest Accurate has special containment and disposal procedures to responsibly discard expended antifreeze.
- Clean up spills or leaks immediately.
- Bring leaking vehicles into the mechanic for immediate repair.
For accidental ingestion or suspected ingestion, contact Poison Control at 1-800-222-1222 or go to an emergency room for medical help. If you believe a pet or wild animal has ingested coolant, contact your vet or an animal emergency clinic immediately. You may also contact the ASPCA Poison Control at 1-888-426-4435. The ASPCA notes they may charge a fee for consultation.
Maintain Your Coolant to Keep Your Cool!
Antifreeze is an important part of your vehicle’s cooling system and the overall performance and longevity of your engine. Blended with the proper balance of water, it creates a powerful coolant solution that protects your engine from overheating, prevents freezing and supports the introduction of key additives that stop corrosion and internal damage. With regular maintenance, you can ensure this essential engine fluid helps your car perform at its peak. And if you have a problem, call Honest Accurate Auto Service. We’ll help you diagnose your coolant issues and find a solution that gets you back on the road.
