Is Coolant Flammable? Fuel for Thought

As car owners, we often have questions about the safety and maintenance of our vehicles. One common concern is whether the coolant used in our cars is flammable.

While this is an important question, it’s important to understand the science behind coolants and their role in keeping our engines running smoothly.

In this article, we’ll explore the properties of coolant and how it reacts under different conditions. So, let’s dive in and learn more about the fascinating world of car maintenance.

Is Coolant Flammable?

What Is Coolant?

Coolant, also known as antifreeze, is used in various mechanical systems, particularly engines, to regulate and control their operating temperature. It is a fluid that circulates through the engine, absorbing excess heat and transferring it away from critical components.

The primary purpose of coolant is to prevent overheating of the engine, which can cause damage and reduced performance. It also helps maintain the engine at an optimal operating temperature for efficient combustion and lubrication.

Coolant is typically a mixture of water and additives, such as ethylene glycol or propylene glycol, which lower the freezing point and raise the mixture’s boiling point.

These additives also provide additional benefits such as corrosion protection, lubrication, and prevention of scale and deposits within the cooling system.

Is Coolant Flammable?

There are two main types of coolants: water-based and non-water-based. Water-based coolants are usually a mixture of water and ethylene glycol or propylene glycol. On the other hand, non-water-based coolants are made up of oils or other substances that are not water-based.

Non-water-based Coolants

Non-water-based coolants, such as oils, are flammable. These coolants, like hydraulic systems, are typically used in low-temperature applications and are not designed to withstand high temperatures.

It is important to be aware of the flammable nature of non-water-based coolants and to take proper precautions when handling them. This includes storing them in a cool, dry place away from sources of heat and flame.

Water-based Coolants

Water-based coolants, such as ethylene glycol and propylene glycol, are not flammable. These coolants have a high boiling point and are designed to withstand high temperatures. This makes them ideal for use in engines and other high-temperature applications.

However, it is important to note that while water-based coolants are not flammable, they can still be hazardous if ingested.

Ethylene glycol, for example, is toxic and can cause serious health problems if consumed. It is important to handle these coolants carefully and dispose of them properly.

How Flammable Is 50-50 Coolant?

The answer is that it varies depending on the specific brand and formulation of the coolant. However, the flash point of most 50/50 coolants is around 220°F (104°C).

This means that 50/50 coolant is not highly flammable but can still catch fire if exposed to high temperatures or an open flame.

It’s important to note that 50/50 coolant is not meant to be used as a fuel or ignition source and should never be used in place of gasoline or other flammable liquids.

It’s also worth noting that while 50/50 coolant itself may not be highly flammable, it can still contribute to fires if it leaks or spills onto hot engine parts. This is because the mixture of water and antifreeze can create a flammable vapor that can ignite when exposed to heat.

Is Coolant Corrosive

Coolant can be corrosive, especially if it becomes contaminated or if its pH level is not properly maintained. Coolants typically contain additives that help protect the engine and cooling system components from corrosion.

These additives form a protective layer on metal surfaces, preventing them from directly contacting the coolant.

However, coolant can break down over time and lose its protective properties. If the coolant becomes contaminated with impurities or if its pH level becomes too acidic or alkaline, it can lead to the corrosion of metal components within the engine and cooling system.

Corrosion can cause leaks, blockages, and damage to various parts, such as a radiator, water pump, heater core, and engine internals.

To prevent coolant corrosion, it is important to use the recommended coolant type and maintain the proper coolant-to-water ratio as specified by the manufacturer.

Regularly testing the coolant for its pH level and concentration is also recommended.

If the coolant becomes contaminated or loses its effectiveness, it should be flushed and replaced with fresh coolant.

What Is Coolant Used For

Coolant is primarily used for regulating and controlling the temperature in various mechanical systems, particularly in engines.

Its main purpose is to prevent overheating and maintain the engine at an optimal operating temperature.

Here are some specific uses of coolant:

Engine Cooling: Coolant circulates through the engine, absorbing heat generated by combustion and friction within the engine components.

It helps prevent the engine from reaching excessively high temperatures that can cause damage and reduced performance. The coolant carries the absorbed heat to the radiator, dissipating it into the surrounding air.

Heat Transfer: Coolant is also used in other heat transfer applications, such as in radiators, heat exchangers, and HVAC systems. It helps transfer heat from one component to another, allowing for efficient cooling or heating processes.

Freeze Protection: Coolant, particularly antifreeze formulations, contains additives that lower the freezing point of the coolant mixture. This prevents the coolant from freezing in cold weather conditions, which can lead to the expansion and potential damage of cooling system components.

Corrosion Protection: Coolant additives protect the engine and cooling system components. They help prevent the formation of rust and scale, which can damage the system and impede its performance.

Lubrication: Some coolants contain lubricating agents, such as the water pump, that help reduce friction between moving parts within the cooling system. This helps ensure smooth operation and longevity of the components.

Heat Recovery: In certain applications, coolant can recover waste heat from industrial processes and transfer it to other areas for utilization, improving overall energy efficiency.

Types Of Coolant

There are several types of coolants used in various applications. The choice of coolant depends on the specific requirements of the system and the manufacturer’s recommendations. Here are some common types of coolant and their uses:

Ethylene Glycol-based Coolant: This is the most commonly used coolant in automotive applications. It provides excellent heat transfer properties and has a wide temperature range.

It is mixed with water to create the coolant solution. Ethylene glycol-based coolants often contain corrosion inhibitors to protect the cooling system components.

Propylene Glycol-based Coolant: Similar to ethylene glycol-based coolant, propylene glycol-based coolant is also widely used in automotive applications. It is less toxic than ethylene glycol and is often used in applications where there is a risk of accidental ingestion, such as in food processing or RVs.

Organic Acid Technology (OAT) Coolant: OAT coolants are long-life coolants that use organic acid inhibitors to protect against corrosion. They offer extended service intervals and are commonly used in modern vehicles. OAT coolants are usually orange or red.

Hybrid Organic Acid Technology (HOAT) Coolant: HOAT coolants combine the advantages of OAT and inorganic acid technology (IAT) coolants. They use a blend of organic and inorganic additives for enhanced corrosion protection. HOAT coolants are commonly used in vehicles with aluminum engines and components.

Inorganic Acid Technology (IAT) Coolant: IAT coolants use inorganic additives, such as silicates or phosphates, for corrosion protection. They require regular maintenance and more frequent coolant changes than OAT or HOAT coolants. IAT coolants are commonly used in older vehicles or in industrial applications.

Nitrite-free Coolant: Nitrite-free coolants are specifically designed for heavy-duty applications, such as large diesel engines. They provide effective liner cavitation protection without the use of nitrates, which can be harmful to the environment.

Is Coolant Poisonous To Animals

The answer is yes. Coolant can be poisonous to animals. Coolant, also known as antifreeze, contains ethylene glycol, a toxic chemical that can be deadly if ingested. Ethylene glycol is sweet-tasting, attracting animals, especially dogs and cats.

Even a small amount of coolant can cause severe animal health problems, including kidney failure, seizures, and even death.

It’s important to note that animals can be exposed to coolant in various ways. For example, if a car has a coolant leak, the fluid can drip onto the ground, creating a puddle that animals may consume.

Animals may also come into contact with coolant while exploring the garage or other areas where vehicles are stored.

What Temp Does Coolant Catch Fire?

The two most common types of coolant are ethylene glycol and propylene glycol. Ethylene glycol is a more traditional coolant, while propylene glycol is a newer, more environmentally friendly coolant.

Ethylene glycol has a higher boiling point than propylene glycol, which means it can withstand higher temperatures before it boils and evaporates.

However, this also means that it can catch fire at higher temperatures. Generally, ethylene glycol can catch fire at temperatures above 250°C (482°F).

Propylene glycol, on the other hand, has a lower boiling point than ethylene glycol, which makes it less likely to catch fire. It typically begins to boil at around 188°C (370°F), but it won’t catch fire until it reaches temperatures above 350°C (662°F).

It’s essential to note that while coolant can catch fire at certain temperatures, this is relatively rare.

Coolant is designed to be a non-flammable liquid, and it’s not something that you need to worry about under normal operating conditions.

However, the coolant can ignite in extreme circumstances, such as a coolant leak onto a hot engine component.

Can Spilled Coolant Cause Fire?

Spilled coolant, particularly if it comes into contact with an open flame, hot surface, or ignition source, can potentially cause a fire. While coolant is not a highly flammable substance, it contains additives and glycol-based compounds that are combustible.

The flammability risk arises when these substances are exposed to a heat source that can initiate ignition.

If coolant is spilled onto a hot engine component, such as an exhaust manifold or electrical components, the heat can vaporize the coolant, creating flammable vapors.

If these vapors come into contact with a spark or flame, they can ignite and potentially start a fire.

Avoid Spilling Coolant: Handle coolant containers carefully to prevent spills. Use appropriate containers and funnels when pouring coolant to minimize the risk of splashing or accidental spills.

Properly Dispose of Spilled Coolant: If coolant is spilled, it should be promptly cleaned up and properly disposed of according to local regulations. Avoid leaving coolant in puddles or areas that can contact hot surfaces or ignition sources.

Maintain a Safe Working Environment: When working with coolant or performing maintenance on a cooling system, ensure proper ventilation to prevent the buildup of flammable vapors. Avoid working near open flames, sparks, or hot surfaces.

Be Mindful of Hot Surfaces: Be cautious when handling coolant near hot engine components. Allow the engine to cool down sufficiently before adding or working with coolant.

Does Coolant Burns

The answer is yes. Coming into contact with the hot coolant can cause burns similar to those caused by hot water or steam. The severity of the burn will depend on the length of exposure and the temperature of the coolant.

If you spill hot coolant on your skin, taking immediate action is important. First, rinse the affected area with cool water for at least 20 minutes.

This will help to reduce the temperature of the skin and minimize damage. If the burn is severe, seek medical attention immediately.

It’s also important to note that coolant can cause damage to your car’s paint or other materials if it’s not cleaned up quickly.

For example, if you spill coolant on your garage floor, it’s important to clean it up as soon as possible to prevent any stains or damage.

How Do You Know If The Engine Is Burning Coolant?

If your engine is burning coolant, it can indicate an underlying issue with the cooling system. Here are some common indications that your engine may be burning coolant:

White Smoke from the Exhaust: If you notice thick white smoke coming from the exhaust, especially when the engine is warmed up, it can be a sign of coolant being burned. This smoke may have a sweet smell, indicating the presence of coolant in the combustion chamber.

Sweet Smell: If you detect a sweet, almost syrupy smell from the engine bay or the exhaust, it can indicate coolant is being burned. This smell is caused by ethylene glycol, a key component of coolant.

Overheating Engine: Burning coolant can disrupt the cooling system’s ability to regulate the engine temperature properly. If your engine consistently overheats or experiences rapid temperature fluctuations, it could be due to a coolant leak and subsequent burning.

Loss of Coolant: If you frequently need to add coolant to your cooling system but don’t notice any external leaks, it may suggest that the coolant is being burned within the engine.

Milky Oil: Coolant mixing with engine oil can cause a milky appearance in the oil on the dipstick or under the oil cap. This can indicate a coolant leak into the engine, which may lead to coolant being burned during combustion.

If you observe any of these signs, having your vehicle inspected by a qualified mechanic as soon as possible is crucial. Burning coolant can indicate issues like a leaking head gasket, cracked cylinder head, or other cooling system problems.

Safety Precautions For Coolant

When handling coolant, it is important to take safety precautions to protect yourself and others. Here are some safety guidelines to follow:

Read and Follow Manufacturer’s Instructions: Read and understand the instructions and warnings provided by the coolant manufacturer. Follow their recommendations regarding safe handling, storage, and disposal.

Use Personal Protective Equipment (PPE): Wear appropriate protective equipment, such as gloves and safety goggles, when handling coolant. This helps protect your skin and eyes from potential contact with the coolant.

Ventilate the Area: Ensure that the area where you handle coolant is well-ventilated. This helps prevent the buildup of potentially harmful vapors.

Avoid Ingestion and Skin Contact: Avoid ingesting coolant or allowing it to come into direct contact with your skin. Coolants may contain toxic substances, and skin contact or ingestion can lead to health risks. If accidental skin contact occurs, wash the affected area with soap and water. If ingested, seek medical attention immediately.

Prevent Spills: Take precautions to prevent coolant spills. Use appropriate containers and funnels when pouring coolant. Ensure that caps and lids are properly secured to avoid leaks. Clean up spills promptly and dispose of the coolant properly according to local regulations.

Be Mindful of Hot Surfaces: Be cautious when handling coolant near hot engine components. Allow the engine to cool down sufficiently before adding or working with coolant.

Keep Away from Open Flames and Sparks: Coolant, particularly when vaporized, can be flammable. Keep coolant away from open flames, sparks, and ignition sources to reduce fire risk.

Store Coolant Properly: Store coolant in a cool, dry, and well-ventilated area. Follow the manufacturer’s recommendations for proper storage conditions. Keep coolant containers tightly sealed and away from incompatible substances.

Dispose of Coolant Safely: Dispose of used coolant according to local regulations. Coolants should not be poured down drains, sewers, or onto the ground.

Many communities have specific recycling or disposal programs for used coolant. Contact your local authorities for guidance on proper disposal methods.

Following these safety precautions can minimize the risks of handling coolant and ensure a safer working environment.


Coolant, particularly ethylene glycol-based coolant, is considered to be flammable. While coolant itself is not used as a fuel, it can ignite when exposed to an open flame or spark. It contains additives and glycol-based compounds that have combustible properties.

However, the flammability risk is relatively low under normal operating conditions when proper handling, storage, and maintenance procedures are followed.

Taking appropriate safety precautions, such as avoiding ignition sources and maintaining proper ventilation, helps mitigate the risk of coolant-related fires.