First and foremost, let’s go over exactly what engine coolant is, and the purpose for it being used in vehicles. Fundamentally, engine coolant (also known as “antifreeze”) is a substance that is mixed with water in order to assist in regulating the overall temperature of a vehicle’s engine.

Coolant functions harmoniously with the existing water in the vehicle’s engine to expand the temperature range within which the water will remain in liquid form. It provides a tremendously valuable service, in that it enables vehicles to successfully operate in a wide variety of extreme temperatures.

Why Do Cars Need Engine Coolant?

Next, let’s discuss why engine coolant is so vital to the ability of a vehicle to function properly over a long period of time and in various adverse weather conditions.

As we all know, water is naturally a wonderfully effective coolant for most normal scenarios. However, we also know that for as many benefits that water provides as a substance, it can be an extremely destructive substance when it transitions to a gaseous or solid form.

While the terms “engine coolant” and “antifreeze” can be used interchangeably to describe the same substance, they are indicative of both functions that coolant provides.

Without the addition of antifreeze to the engine, imagine the impact that below freezing temperatures would have on the water within the engine. Freezing temperatures would cause the water in the engine to turn into ice, causing it to expand within the engine, ultimately causing massive destruction to various compartments throughout the vehicle.

The addition of antifreeze (motor coolant) prevents this from taking place, by dropping the temperature at which the water in the engine would freeze. This enables the vehicle to function successfully at much lower temperatures.

Conversely, on the other end of the heat spectrum, we all know that when water reaches a certain level of heat, it begins to transition from liquid form to a gas (steam).

While capable of immense energy and extreme power, steam can be an equally destructive force in an environment not built to withstand it. When engine coolant is added to the vehicle, it increases the temperature at which water begins to evaporate, thus enabling the vehicle to successfully operate at extremely high temperatures.

What Is the Best Way to Change Engine Coolant?

When it comes to changing engine coolant, we always recommend consulting the advice of experienced automotive maintenance professionals. However, if you have experience working with vehicles, then an coolant change might just be within your wheelhouse. Listed below are the general steps associated with the process of changing engine fluid.

Prior to attempting a coolant exchange, you will want to make sure that your engine and radiator are both fully cooled down. Next, you will need to remove the radiator cap, often located near the front of the engine compartment. Once this is complete, you will need to place a bucket or receptacle of some sort underneath the radiator, and loosen the drain plug. This will ensure that all the engine coolant is drained from the radiator.

Next, you will need to drain all of the coolant from the engine. In order to do this, you will need to move the receptacle directly under the engine drain bolt, then loosen the bolt. This will enable all of the remaining coolant to drain from the engine block.

After the engine coolant is fully drained from both the radiator and engine block, the next steps are to ensure that both, the radiator drain plug, and the engine drain bolt are tightened. Then you will begin the process of adding the new coolant. Add the coolant to the radiator until the fluid reaches the filler neck line.

Once this step has been completed, you will need to start your engine and let it idle in order to allow it to purge any excess air from the engine block. During this process, we encourage you to check for any possible leaks throughout the engine compartment. If any leaks are found, try to note their locations and have them inspected by an automotive repair specialist. If there are no leaks to be noted, then you can consider the engine coolant exchange process to be complete.

What Are the Different Types of Coolant?

Believe it or not, there are quite a few different types of coolant available on the market. While they all effectively serve the same purpose, different engine types require marginally different coolant with variations in mixture and viscosity. Listed below are the most prominent variations of motor coolant that are used in the automotive industry today.

• IAT (Inorganic Additive Technology) uses silicates as the primary source of active inhibiting technology. IAT coolant is predominantly used in older vehicles and is green in color.
• OAT (Organic Acid Technology) uses organic acids as the primary source of active inhibiting technology. OAT coolant is used in General Motors, Saab, and Volkswagen manufactured vehicles, and is orange in color.
• HOAT (Hybrid Organic Acid Technology) uses both silicates and organic acids as the primary sources of active inhibiting technology. HOAT coolant is predominantly used in Ford, Chrysler, and many European manufactured vehicles, and is yellow in color.
• HOAT (Hybrid Organic Acid Technology – Phosphate Free) is slightly different from its other HOAT counterpart in that it is nitrite, amine, and phosphate free. This phosphate free version of HOAT is predominantly used in BMW, Volvo, Tesla, Mini, and some other european manufactured vehicles, and is turquoise in color.
• P-HOAT (Phosphated Hybrid Organic Acid Technology) uses both phosphates and organic acids as the primary sources of active inhibiting technology. P-HOAT coolant is predominantly used in Toyota, Nissan, Honda, Hyundai, KIA, and numerous other asian manufactured vehicles. P-HOAT is either pink or blue in color.
• Si-OAT (Silicated Organic Acid Technology) uses silicates and organic acids as the primary sources of active inhibiting technology. Si-OAT coolant is predominantly used in Mercedes-Benz, Audi, Volkswagen, Porsche, and other high-end European manufactured vehicles. Si-OAT is purple in color.

With so many different types of coolant on the market, it is imperative that you follow the guidance of automotive professionals, and pick the appropriate type for your vehicle.

What Kind of Motor Coolant Should I Use?

In order to ensure that you choose the correct coolant for your vehicle, we first recommend that you refer to the general guidelines listed earlier in this article. We also recommend referring to your vehicle’s owner manual.

While on the surface, the need for choosing a specific engine coolant variation for your vehicle may seem unnecessary, in truth it is vitally important. Using the appropriate fluid for your vehicle is vital in order to ensure it operates as intended.

High-end performance automobiles, for example, place much larger strains on an engine than do regular daily commuter vehicles, thus requiring an engine coolant with different active compounds. Conversely, trucks and towing vehicles also place their own unique strains on an engine, therefore requiring their own type of specific cooling fluid.

It is for these reasons, and many more, that choosing the correct engine coolant for your vehicle is imperative.

How Long to Wait Before Adding Coolant to a Hot Engine?

It is very important to make sure that all of the proper precautions are taken throughout the engine coolant changing process. While the process is fairly straightforward and simple, coolant can get extremely hot while the vehicle is in use. It can remain dangerously hot for a long time after the engine has been turned off.

The recommended time to wait before removing the radiator cap will vary greatly depending on whom you ask, and change with each person’s risk tolerance level. The truth of the matter is that the rate at which engine coolant returns back to a “safe” temperature fluctuates significantly across many different vehicle models.

For example, the amount of time that the engine was on is one factor that can affect the time required for the coolant to return to a safe temperature. Also, the nature of how intensely the engine was having to work while the vehicle was being operated is another factor.

Wait times prior to removing the radiator cap can vary from fifteen minutes in some instances, all the way to three or four hours. So in order to be safe, we recommend to wait overnight, and perform the coolant change the next day, prior to the vehicle being driven again. While this may seem excessive, it is the best way to ensure the highest probability of safety during the process.

As always, when in doubt, the owner’s manual that accompanies your vehicle will always be the most definitive and pertinent resource to consult when making your final decisions on when to remove the radiator cap and commence with the coolant exchange.

Which Coolants Need to Be Diluted with Water?

Historically, engine coolant (antifreeze) was sold in its concentrated form. This required the end user to oversee the dilution process with water before adding it to the vehicle . However, nowadays, the majority of coolant available for the everyday consumer to purchase comes pre-diluted in a 50/50 percent ratio.

In unique conditions, certain experienced vehicle owners and operators may want to have the ability to dilute their own engine coolant to meet their unique needs. An example of this would be in conditions of extreme cold and extreme heat. In these extreme environments, users may elect to have a greater amount of coolant in the mixture than water.

If done correctly, these custom dilutions can slightly enhance the performance of the engine, reduce the frequency with which engine coolant must be changed, and decrease the chances of temperature related damages to other areas of the vehicle.

As a general rule of thumb, we recommend purchasing the correct 50/50 pre-diluted mixture of motor coolant for your vehicle, as this will accomplish the overall goal of keeping your engine operating properly while providing a sense of convenience and reliability.

How to Dispose of Old Engine Coolant?

In the event that you choose to change your engine coolant, you will need to be sure to dispose of the old coolant in a safe and appropriate manner.

Technically speaking, old coolant and antifreeze are classified as “hazardous waste”, and the disposal protocol of these solutions is therefore subject to EPA regulations.

The first thing we recommend you do is to visit your state’s Department of Waste Management website to find a list of procedures for the disposal of engine coolant, along with information about local centers in your area that accept and process coolant for recycling.

Be sure to store and transport the old engine coolant in sealed plastic containers to ensure that no coolant is spilled during transport to the hazardous waste facility. In general, treat coolant with the utmost caution and care in order to maintain your safety and health.

How Often to Change Engine Coolant?

When it comes to how often you should have your engine coolant changed, the industry average is roughly between every 30,000 to 60,000 miles. Again, these numbers vary depending on the model of vehicle, weather conditions, and how the vehicle is driven.

Vehicles residing in extreme climate conditions will most likely need more frequent servicing, as will older vehicles that might produce more residue and particulates that hasten the rate at which the engine coolant will need to be replaced.

As with most other matters regarding maintenance of your specific vehicle, we always encourage you to visit the owner’s manual of your vehicle for the definite mileage range within which the manufacturer recommends the engine coolant to be serviced.

What Are the Signs that Engine Coolant Needs to Be Changed?

There are a few reliable ways in which vehicle owners can tell when it is time to change their engine coolant. Most newer vehicles have the ability to sense low coolant levels, and therefore initiate a warning light (most often on your front dash) indicating that the coolant level is low, and therefore should be replaced.

Another telltale way to know if it is time to change your engine coolant is if the coolant has either turned red or black. Overtime, some vehicles can expel rust particles that can mix with coolant and result in clogging throughout various compartments of the engine. In the event that the coolant has a black tint, this is most often a result of engine oil leaking from the head gasket of the vehicle, and is cause for needing an engine coolant replacement.

If your heater stops functioning properly, this is also a sign that your vehicle’s coolant has ceased to function properly, and should be replaced.

Lastly, if you find that your vehicle begins to overheat with increasing frequency due to the engine coolant no longer being able to effectively regulate the temperature in the engine, this is a strong indicator that your engine fluid will need to be replaced.