Is Engine/Motor Oil Flammable? (Everything to Know)

While pouring engine oil, have you ever thought of what could happen, perhaps a spark occurs suddenly, or a person walks by with a cigarette burning in his hands?

There is a general assumption motor oil is capable of burning. However, is motor oil flammable? If you are asking this question, then you are on the right page because we have the answers you need.

Engine oil falls under combustible liquids and not a flammable liquid, with a low flash point of 419° Fahrenheit (equivalent to 215° Celsius), which exceeds the threshold for flammable liquids at 199.4° Fahrenheit (equivalent to 93° Celsius).

Combustible materials require the presence of air to burn; however, flammable materials are triggered quickly upon exposure to fire.

This article discusses things that should be known about motor oil, such as is motor oil flammable? How about synthetic oil? And if they are flammable, how much heat will be needed to burn motor oil. We also give tips on protecting one from blowing up these liquids and lots more.

Let’s begin!

However, exposure to fire is required for flammable substances, which are combustible also. Nonetheless, engine oil can burn easily when the heat level is enough.

Here, regular engine oil is what we are examining, and it is derived from crude oil. Aside from making friction not happen or reducing it, engine oil also helps clean sludge off the engine, and acid in the fuel is also made harmless.

Another vital role it plays is to cool the engine of the vehicle as it transfers heat away from parts in motion, not forgetting its role in protecting piston rings.

Its several functions make it an important feature in running a vehicle, and knowing how flammable it is to the danger of fire accidents is a safety precaution.

When examining the flammability of engine oil, the vapor released should be the focal point, observing whether the oil release vapor that ignites it automatically.

A lot of oils are made of carbon chains, long and difficult to break, which later release vapor to burn. With this, they cannot be classified as flammable.

Notwithstanding, a point to note is that a few vehicle experts defined a combustible fluid to include any fluid with a higher boiling point than its flash point.

The flash point of engine oil ranges between 302 – 392° Fahrenheit and its boiling point stands at 572° Fahrenheit. This implies that it falls into the category of flammable liquids going by the definition of some experts.

However, can engine oil cause fire? Considering how high the flash point of engine oil is, a lot of heat is required for it to ignite, taking out its possibility of being the initial cause of a fire outbreak.

A lot of times, it usually burns lightly to support a flame that is not so strong.

Also Read: Is Brake Fluid Flammable? (Why You Should Be Careful With Them)

Is Synthetic Oil Flammable?

Is Synthetic Oil Flammable

Synthetic oil has properties of hydrocarbon in it; hence it is flammable. Although its flash point is not so low, it is made to work even at a high temperature without flaring or getting destroyed.

The general rate at which synthetic oil burns is not as high as regular engine oil, which needs a higher temperature to burn.

The flash point for synthetic oil range from about 440° Fahrenheit (equivalent to 227° Celsius) for the regular brands, while the superior brands have increased flashpoints that range from 450 – 500° Fahrenheit ( equivalent to 232 – 260° Celsius).

Synthetic oils are less flammable than other flammable liquids like gasoline having about 40° Fahrenheit ( equivalent to 4.4° Celsius) as their flash point.

Also Read: Can You Add Oil to a Hot Engine?

Is Used Motor Oil Flammable?

If uncertain whether used engine oil has more tendency to burn than a fresh one, the simple answer is NO.

Generally, oxidation softens oil and reduces its stickiness, allowing it to mix more easily with gasoline.

But even when oil has been highly oxidized, it does not burn easily upon exposure to fire because it has a high flashpoint.

Flashpoint simply means a temperature where enough heat has been produced and can make oil burn. Having a high flashpoint means engine oil ignites at high temperatures only.

Engine oil contains a combination of hydrocarbons with longer molecular chains, making it quite a heavy liquid.

Higher temperatures or more energy are needed to turn the oil into vapor. Used engine oil can burn, although it will need a temperature that exceeds the flashpoint of regular oil.

When looking at how flammable liquids are, the major thing to check is how it generates vapor that can automatically ignite the oil. Most flammable oils contain a short chain of hydrocarbons.

These short molecules turn to vapor fast, making ignition at a lower temperature possible.

Can Motor Oil Spontaneously Combust?

The possibility of engine oil igniting all by itself is not so high. However, if the required conditions are met, engine oil or substances containing oil can ignite naturally.

A few liquids go through oxidation upon exposure to air; in simple terms, it is the chemical process in the production of heat energy. It is this oxidation procedure that causes natural ignition.

Engine oil does not go through any oxidation; therefore, it can not burn all by itself. Without any external influence, engine oil can not cause a flame without the aid of some other source of fire.

Can You Burn Motor Oil?

Is Motor Oil Flammable

When trying to properly dispose of used engine oil, thoughts of whether burning it is a good option crosses the mind.

While it is possible to burn engine oil, the smoke it generates from the burning process contains a lot of carbon monoxide, unlike other kinds of smoke.

Due to this fact, it is not just toxic but has some properties that can cause cancer. Hence, burning engine oil openly is not recommended.

So How Can We Burn Oil Safely?

While it is generally unsafe to burn engine oil, some special waste oil burners exist. They are furnaces made to use engine oil, fuel oil, hydraulic oil, and transmission oil to produce heat.

If there is a lot of used oil, using this disposal method is advisable and may also be a good means to produce the heat required in our home or businesses, which minimizes overhead costs!

How Can You Safely Store Oil?

Although engine oil can not flare up on its own, it can burn easily. Several sources of ignition usually burn at temperatures above 400° Fahrenheit (equivalent to 204° Celsius).

This implies that if engine oil should get in touch with that kind of fire, it will get warm and reach the level where it can burn.

Hence, how engine oil should be properly stored directly affects the safety of vehicle owners.

Some safety precautions to remember include:

1. Ensure There’s Sufficient Ventilation

If a large quantity of engine oil is being kept, the level of vapor concentration within such a storage facility is pivotal.

There should be a ventilation system that functions in the

storage space, whether mechanical or natural. However, mechanical ventilation systems should be safe and may come at a very high price.

Natural ventilation is highly recommended, and this may be done by creating an opening in the store walls, and fixing louvers in those spaces can help prevent the buildup of vapor.

2. Spill Containment

Storage spaces where combustible liquids are stored must have a reservoir at the base of the store to accommodate any oil spillage.

The reservoir’s capacity is determined by the amount of oil being stored.

3. Protection From Ignition Sources

To reduce fire hazards to people and property, keeping engine oil in a secure space and far from any ignition source is important.

Ignition sources include open fire, hot materials, and static spark-generating equipment.

Using electrical heating when possible rather than open fire is advised. The storage space should not be less than 3 meters from any ignition source.

When a small quantity of oil is being stored, put the oil container in a bucket with a little sand in it. The sand is necessary to take in any oil spillage and reduce the effect of any fire outbreak.

How to Deal With an Engine Oil Fire

Is Motor Oil Flammable

In a situation where engine oil ignites, knowing how to get the situation under control can be very helpful. Although inflammable engine oil can easily catch fire, it can be categorized as a Class B fire when such happens.

Flames categorized as Class B include flammable oils like paraffin and gasoline. Though engine oil does not fall into the category of flammable oil, they are grouped together due to the process required to put out their flames.

All flames that fall in Class B should be put out without water.

As a matter of fact, extinguishing an oil flame with water worsens the situation as the fire will grow taller and become much hotter, and it also makes the fire spread with less difficulty.

To extinguish flames that fall in Class B, having a carbon dioxide fire extinguisher for Class B flames is recommended.

Carbon dioxide neutralizes the oxygen sustaining the fire, which ultimately puts out the fire. Where a Class B extinguisher is not within reach, Seek assistance from the nearest fire department.

Also Read: Oil Smells Like Gas (Causes & Solutions)

Frequently Asked Questions – Is Motor Oil Flammable?

Can motor oil catch fire?

Although engine oil is inflammable, it can burn. The Occupational Safety and Health Administration (OSHA) stated that it is not a flammable oil. Before it is considered flammable, it burns at 200° Fahrenheit meanwhile, oil burns at about 300° to 400° Fahrenheit. This implies that engine oil burns at a very high temperature.

Can oil catch fire from a spark?

Engine oil can burn; however, because its flashpoint exceeds 199.4° Fahrenheit ( equivalent to 93° Celsius), it falls short of OSHA’s class of flammable oil. Engine oil has a flashpoint of approximately 419° Fahrenheit (equivalent to 215° Celsius).

Is used motor oil good to start a fire?

Although it can burn, compared to other flammable liquids, it is not as flammable as some car experts usually say. Nonetheless, with adequate heat, engine oil can easily flare-up.

Are motor oil rags combustible?

Engine oil (including anything drenched in engine oil) will most likely not burn naturally. However, it may burn when the required conditions are met. Therefore, consider safety first and adhere to the directives given above to guard against the occurrence of fire incidents. For rags soaked in gasoline, however, they usually need a source of fire to ignite their fumes.

Why is engine oil not flammable?

Engine oils are known to be more stable than flammable oils due to having 150 °C as their flash point. However, they still need to be stored in safe conditions. Substances like engine oil have stronger intermolecular forces of attraction and usually do not ignite when the temperature does not reach its flash point.

Can rags with motor oil spontaneously combust?

Natural burning of rags soaked in oil will occur through oxidation when the cloth or rag slowly heats up to its burning point. Substances usually start to generate heat due to oxidation. In a situation where this heat gathers and is trapped with no escape route, it raises the temperature to a degree hot enough to burn the oil and make the cloth or rag burn too.

Conclusion – Is Motor Oil Flammable?

Yes, motor oil is flammable. However, it burns at a very low degree, and some auto experts prefer to call it combustible. For better understanding, the difference between combustible and flammable is; that combustible substances can ignite in air.

Engine oil, without a doubt, is an important oil for engines. Aside from being a lubricant, engine oil also plays the role of a buffer for acids; both synthetic and regular engine oil can burn; however, the temperature has to be quite high.

With all these being said, moving around with a lighted cigarette near engine oil is not capable of making the oil burn.

Nonetheless, it can still burn if it makes contact with fire directly or in a situation where its temperature rises above its flashpoint of 400° Fahrenheit (equivalent to 204° Celsius).

Engine oil is capable of burning but does not pass as a flammable oil. Remember to be cautious and ensure to keep yourself safe and those around you.

Scott Greene is a seasoned automotive technician for over 5 years and has been deep into advanced automotive diagnostics for a couple of years. He Loves writing about Automotive Diagnostics and Repair, Trouble codes, Buyer guides for various car parts and accessories, and lots more. 

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