Is Motor Oil Flammable? Know About the Shocking Facts

How often has it happened that you were working with your motor oil, and suddenly a question crossed your mind – what if the oil catches fire near a cigarette. Can this happen when I am driving the car?

It is quite obvious that you think the motor oil is flammable. If you are among these people, the information I am about to give you might be shocking enough.

So, is motor oil flammable? If you go by the definition, motor oil is not a flammable liquid. Scientists suggest that motor oil can be a combustible liquid, but it is never a flammable one since it will require a much higher temperature to get the oil to catch a fire.

In this article, I am going to talk about if the motor oil is flammable, about the synthetic oil flame, and how to deal with the oil when you are driving. So, stick through the end to get exciting information!

Is Motor Oil Flammable?

No, technically speaking, motor oil is not flammable. If you go by the definition, flammable liquids are those that burn up with the contact of a burning source that might be below 37.8 degrees Celsius or 100 degrees Fahrenheit.

On the other hand, motor oil can combust, but it will require a much higher temperature for that. Also, some experts claim the motor oil to be a “Combustible liquid” that might burn up in the presence of a burning source at around 150-205 degrees Celsius or 300-400 degrees Fahrenheit.

A flashpoint is a temperature at which a substance gets enough fumes to combust whenever a burning source or spark is nearby. When it comes to motor oil, the flashpoint is somewhere around 400 degrees Fahrenheit.

However, you shouldn’t be confused with the auto-ignition temperature because that means the temperature at which the element starts burning naturally. You will need q much higher temperature to let your motor oil do that!

Why Isn’t Motor Oil Flammable?

According to scientists, flammable liquids burn because of the small chains of hydrocarbons present in them. These tiny molecules can easily release a vapor, which in turn makes them combust in even low temperatures.

Now, they can release vapor due to the really weak intermolecular forces, which means that you can easily break two molecules apart, and one of them goes away like a vapor. Now, imagine this situation in a liter of liquid where there are millions, even trillions of molecules present. So, this vaporing can happen in a second with a huge amount.

If you examine the motor oil, it is made with a mix up of hydrocarbons. While there is no specific type, the combination is supposed to have a carbon with almost 18 to 34 carbon atoms in each of the molecules. Moreover, motor oil is really heavy, and it contains longer molecules than flammable ones.

Subsequently, the motor oil comes with strong intermolecular forces that make it super hard to break two of these molecules or turn any of them into vapor at room temperature.

Though you can combust the motor oil, it will need a much higher temperature, which will be effective in weakening the intermolecular forces enough so that a vapor is produced.

Because of this, the motor oil is mostly regarded as a combustible liquid rather than a flammable one.

Can you light a motor oil on fire?

At room temperature? You can’t. As I mentioned earlier, every oil has a certain flashpoint at which it might light up in contact with an igniting source. But I don’t think it is possible for you to create that much heat in your garage or all by yourself.

So, in case you want to light a motor oil on fire, you will have to get the temperature to at least 400 degrees Fahrenheit and then manage a source like oxygen.

Is Synthetic Motor Oil Flammable?

No, it is not. The fun fact is that synthetic motor oil is even less flammable than the general standard motor oil. This happens because they are made in a way to be superior temperature resistance. However, like any other motor oil, they will also start burning at a temperature hot enough.

Surprisingly, most of the synthetic motor oils we use nowadays have a flashpoint around 450-500 Fahrenheit, and if you get the stronger ones, they won’t break until 700 degrees Fahrenheit! That’s why synthetic oils are the most recommended ones.

You should know that the amount of heat produced by a car engine can be enough to make any ordinary oil reach its breakdown position. Though that does not make the oil burn due to the absence of an ignite source, the molecular chains get split up into shorter ones quite easily.

These small chains include a lower viscosity level that makes them something like the water. It also means that your engine can run much faster even though it offers less safety to the components.

Moreover, the traditional motor oil has a boil-off that means that their intermolecular molecules get much weaker when the shorter chains of the hydrocarbon molecules are exposed to the air. It is also easier to form vapor in that way.

However, you shouldn’t worry about your oil becoming flammable in a car. The ventilation system in the engine makes sure that the vapor can’t be built up enough to catch fire. But if the molecules manage to leave the engine as vapor, they will never come back.

One advantage of the lower flammability of synthetic oils is that they are way cleaner than traditional motor oils.

What Temperature Does Motor Oil Catch Fire?

While the exact number varies from the quality and brand, most of them have a flashpoint around 400-500 Fahrenheit when they get a specific source of heat. Some experts say that they tested the motor oil and found its flashpoint at 419 Fahrenheit or 215 degrees Celsius.

However, you can be assured that motor oil will never produce vapors at room temperature, and it can never catch a fair just because someone lit a cigarette or there is a spark nearby.

But we also strongly discourage people from smoking in places like the garage. Just because there is no harm, that does not mean something else can’t cause it.

Is Engine Oil Flammable?

Just like motor oil, engine oil is not flammable depending on the definition, but it isn’t totally immune to fire. There are some ignite sources that can be generally hotter than 400 degrees Fahrenheit, and if by any chance it matches with the engine oil’s flashpoint, it will start to burn.

If the engine oil will burn depends highly on the storage system you are using. So, to keep the engine oil away from burning, you will need:

Adequate ventilation: It is okay if you are using just a small amount of oil in a single bottle. But if you are backing up a huge amount, then you will need necessary extractions to keep the oil away from building up vapors.

Spill containment: If you are riding with a single bottle of oil, it is better to keep it in a bucket of sand. In this way, the oil will never catch fire even if it leaks out of the bottle. In case you have a huge amount with you, you need to take help from a professional supplier for spill containment services.

Keeping them away from igniting sources: If you feel like they’re a source of flame near you, it is wise to keep the oil at least 10 yards or 3 meters away from it. You can guess that this will keep the potential fire and its sources away from you.

SO, hopefully, you can be quite safe around the traditional motor oil upon taking all these safety measures.

Here’s a small chart to give you a clearer idea about the temperatures in which a motor oil wills start burning

MaterialAutoignition Temperature
Conventional Oil580-635
Engine Oil760-870
Used Conventional Oil600-637

Conclusion

So, I hope now you got a clear answer to “Is motor oil flammable?” While motor oil can get combust at a certain temperature, it does not come in the definition of a flammable liquid (Catches fire at 100 degrees Fahrenheit or less).

However, you shouldn’t be too care-free and leave sparky things around the motor oil. So, it is better if you don’t go around smoking cigarettes in your garage or in a parking lot. But it is a lot easier when you are using synthetic oil.

So, you have to store your motor oil very carefully to reduce the risks of getting fire for yourself and also others around. I hope this article has helped you with useful information and you got the answer to everything you were looking for.

James L. Rocha

Hey, I am James L. Rocha, breaking down all your queries is just as easy as that. I am running Auto Kits Lab especially to help you with all the necessary information you may need. I portray my experience here with passion and care that will surely meet your expectations.

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