What is Antifreeze? Why Does My Vehicle Need It?

What is Antifreeze?

Antifreeze is one of the vital fluids that keeps your car’s engine running in top condition. Without it, temperature regulation in the engine is impossible–which spells disaster and the end of your car’s existence.

Antifreeze prevents the water in your radiator and engine from boiling during the warm weather months and keeps this same water from freezing during the winter. As a coolant, this important fluid effectively works with liquids up to 275 degrees Fahrenheit. In cold temperatures, it remains effective down to 30 degrees below zero.

Although temperature regulation may be the principal function of antifreeze, it is not the only one. Antifreeze also lubricates parts of the engine, specifically the water pump, to prevent friction and overheating, and damage. Moreover, antifreeze protects against corrosion since its particles self-corrode, as opposed to corroding the metal parts that come in contact with them. This means that aluminum cylinder heads, which are vulnerable to corrosion, are protected from any such damage. This is why keeping your antifreeze at its proper level in your engine is imperative to the life of your vehicle.

How do the chemical components of antifreeze work to keep the engine at a constant, safe temperature? Antifreeze is made of propylene glycol or ethylene glycol. This chemical base serves the purpose of raising the boiling point of this liquid as well as lowering its freezing temperature which allows antifreeze to act both as a coolant and a guard against freezing. Antifreeze also contains additives such as nitrates, azoles, silicates, or borates, though they make up less than 10 percent of the entire solution.

These additives specifically guard against oxidation and corrosion that water alone would cause. When you add antifreeze to your vehicle, for the most part, you will mix it with water at a 50/50 ratio. Because some brands come premixed with water, you should check the label before pouring it into your vehicle. In fact, becoming familiar with the general guidelines and usage of antifreeze would prove to be a valuable part of learning more about vehicle maintenance.

How To Check Antifreeze Levels?

Checking your antifreeze level regularly is an important maintenance measure, and you do not have to wait for the temperature alert sign on the dashboard to flash to do so. However, before you open the hood, make sure the vehicle has cooled down completely since antifreeze can get quite hot after the car has been running. Also, make sure the car is sitting on level ground so as to get an accurate reading.

Once you open the hood, you will need to locate the coolant reservoir and the radiator.

If your vehicle is an older model, you won’t have a reservoir. In this case, you can open the cap to the radiator, and using a flashlight, you can look inside to see the level of antifreeze.

If you do have a reservoir, which is the case for most vehicles, you can simply look at its exterior to locate a line that indicates the maximum level. You will also find a line that shows you when the level is low. After a closer inspection of the sludge and the color of the antifreeze, you can top off your radiator if the antifreeze is at the low-level line in the reservoir.

What Makes Each Antifreeze Type Different?

Along with familiarizing yourself with the process of checking the antifreeze level, you should also know which type your vehicle requires. All coolants have the same ethylene glycol base. However, you may have noticed that different types come in different colors. Each color indicates the types of preservatives that are in the formula. Thus, it is important to differentiate between each type based on your vehicle’s specific requirements. Moreover, it is imperative to read the label before topping off your reservoir.


To start off, the green antifreeze is made for older models made before 2000. This formula which consists of Inorganic Additive Technology is more geared toward the engine that has copper and steel components–which explains the high level of preservatives that protect against corrosion.

The orange antifreeze, which contains an Organic Acid Technology base, is made specifically for vehicles made with aluminum and nylon cooling systems. Typically, this type comes in a silicate-free or phosphate-free (or both) formula.

Plus, you have the manufacturer-specific types of antifreeze/coolant. The colors indicate which make it is specifically designed for.  For example, antifreeze for Toyotas comes in red, while purple is geared toward Volkswagen vehicles, and the brands for Subaru come in blue. All of these types come free of silicates, phosphates, or both.

Signs That Your Vehicle Needs More Antifreeze/Coolant

Knowing more about the types of antifreeze and how to check its level is important to regular maintenance, but knowing the signs that your vehicle needs more coolant/antifreeze is vital. These include the following.

The Dashboard Warning Light

All vehicles have an indicator on the dashboard that shows the status of your engine’s temperature. The three lines that you will need to watch for are the “C (cool) at the bottom,” the middle line (which shows the normal temperature range), and the “H (hot).” If the indicator keeps rising from the middle to the “H,” then you should check your cooling system and add more coolant.

Also, in some vehicles, a light comes on that resembles a thermometer. This, in addition to the temperature gauge, shows you that you need to turn off the engine immediately, check the cooling system, and fill up the coolant.

Strange Odors

You may notice a strong, sweet scent as you are driving. This odor means that you need to shut the vehicle off immediately and have it taken to a professional mechanic to check the coolant level and the cooling system. The smell comes from the coolant and indicates that you have a leak somewhere in your vehicle’s cooling system.

Changes in Appearance

As you check your coolant/antifreeze level, you might pay attention to its color and any other changes in appearance. Do you notice a rusty color or tiny flakes floating around? It might be time to flush the radiator and change your antifreeze.

Additionally, if you find dark sludge on the cap of the radiator, you will need to change the fluid completely. Plus, you can check the color more accurately by opening a drain valve and emptying a small amount of antifreeze into a clean, clear container. The color should be bright orange, yellow, or green depending on the type and brand of the antifreeze. If it is muddy or rusty, you will need to change it out.

How Often Should Antifreeze Need To Be Changed?

Antifreeze in cars

A typical antifreeze should be changed every 30,000 miles. Generally, an owner’s manual would recommend changing it after the first 60,000 miles and then after every 30,000 miles. Likewise, some types may not need to be changed until after 120,000 miles. The best way to find out exactly how often is to check your own vehicle’s owner’s manual which also stipulates what type of antifreeze would work best for your engine.

How To Top Up Antifreeze To My Vehicle

When adding antifreeze to your vehicle, you would first follow the steps for checking the level which involves letting the car cool completely and then locating the reservoir. Also, you will need to wear gloves and goggles for protection.

Once you have found the reservoir and its cap, touch it to see if it is still warm. If it is, do not open the cap as this may cause a steam burn, or liquid might come flying out.

If the engine is cool, you can slowly (not abruptly) turn the cap to gently release any pressure underneath. Next, you can mix your coolant solution by mixing equal parts of antifreeze and distilled water in a clean container. On the other hand, if you have a premixed antifreeze, you do not need to add water. Once your antifreeze is prepared, slowly pour it into the reservoir until it reaches just a few inches below the “Max” line.


One final tip is to avoid “universal” or “long-lasting” antifreeze brands that tend to be inexpensive but fail to protect your engine. Consider trying Shield’s Polar Cool, which protects your engine during every season. Although Shield’s Polar Cool comes in fluorescent green, it is still compatible for newer vehicles as opposed to other traditional green brands. This antifreeze coolant also consists of an ethylene glycol base with a corrosion inhibitor that protects your gaskets, houses, and thrust seal along with any metal components. Plus, compared to other brands, Shield possesses extremely high boiling points and low freezing points to guard high-performance engines in all weather conditions.

Shield Polar Cool

Ready to learn more about our other automotive products, like our automotive lubricants, radiator water, and oils? Contact us today to find out which products would enhance your vehicle’s performance.

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