Is Engine Oil Flammable: Clearing Misconceptions Completely

Is Engine Oil Flammable?” has crossed the minds of many drivers, especially when they detect an engine oil leakage. Many even fear that the slightest spark could ignite huge flames that would engulf the vehicle if the leakage is not repaired fast.

is engine oil flammable

Others also fear storing engine oils because of the same reasons. In this complete guide, we’ll discuss whether or not engine oils are flammable, the various classifications of engine oils, and how to effectively store motor oils, so keep reading!

Is Motor Oil Flammable and Can It Catch Fire?

No, engine or motor oil is not flammable, but it can catch fire when it gets to its flashpoint. For an engine oil to get to its flashpoint, it has to be heated to about 400 degrees Fahrenheit, at which the vapor produced from the heat can catch fire.

– Explaining Why Motor Oils Aren’t Flammable

The truth is liquids don’t burn but it is the vapors they produce that can catch fire. Thus, the easier a liquid gives off vapor, the quicker it’ll burn in the presence of a fire source. Liquids that easily produce vapors have smaller molecules that have weak intermolecular bonds. Therefore, whenever they come in contact with fire, they easily break the bonds and turn into vapor, which then burns.

On the other hand, liquids like motor oils have strong molecular bonds that don’t easily break. This is because such liquids have relatively bigger molecules that bond easily. These bonds can only become weaker when heated and the more heat that is applied, the closer they get to their flashpoint. The flashpoint of a liquid is the exact temperature at which the liquid forms enough vapor to burn.

This explains why motor oils won’t burn at room temperature because they exhibit bigger and stronger molecular bonds. It also demonstrates why liquids like petrol or gasoline will easily burn when they come into contact with fire.

The liquid type which is highly flammable is gasoline, which has a flash point of -45 degrees Fahrenheit. Gasoline burns easily to produce enough power to move vehicles and other machinery. Thus, its flashpoint is very low to enable it to carry out its responsibility.

– Why Engine or Motor Oils Are Classified as Combustible

Engine oils are combustible (can catch fire) when they are heated to their flashpoints but are not categorized as flammable liquids because they don’t meet the criteria. For a liquid to be classified as flammable, it must have a flashpoint higher than 140 degrees Fahrenheit but lesser than 199.4 degrees Fahrenheit.

Engine oils have a flashpoint of 302 degrees Fahrenheit, which far exceeds the 199.4 degrees Fahrenheit level. Thus, they are classified as combustible liquids (can catch fire) but not flammable liquids.

– Importance of Producing Non-flammable Engine Oils

One importance of having non-flammable engine oils is that it prevents overheating in the engine. If the engine oils were flammable, they’ll do a poor job of transferring the heat generated in the engine. This will cause the engine to overheat and eventually cause its breakdown.

Also, flammable engine oils will mean weaker molecular bonding, which translates into a less viscous liquid. If the motor oil is less viscous, it won’t do a great job of reducing friction within the moving parts of the engine.

The moving parts will begin to grind against each other, causing wear and tear and this can increase the temperature within the engine. Eventually, these moving parts will halt to a stop, which will lead to engine failure.

– Flammability of Used Engine Oils

Used engine oils have the same flammability as new engine oils because their flashpoints remain relatively the same. However, used engine oil may have lost its viscosity, which could be detrimental to the engines. Thus, it is best to regularly undertake oil change.

– Flammability of Synthetic Oils

Synthetic oils are even less flammable than traditional oils because they are designed to withstand heat while cooling the engine. However, like regular oils, synthetic motor oil burns if exposed to intense fire that raises its temperature above its flashpoint.

Synthetic motor oils are intentionally designed to endure high temperatures with their strong molecular bonds. These oils have a flashpoint of 450 degrees Fahrenheit, which is higher than the 302 degrees Fahrenheit exhibited by regular oils.

A few motor oils have raised the bar with a flashpoint of 700 degrees Fahrenheit, which makes them extremely difficult to burn. The idea is for the oil to withstand the heat that is generated in the engine and to possess enough viscosity to protect parts of the engine.

Also, motor oils with high viscosities are able to last longer before their molecular structures break down and they become somewhat like water. This means that they are unable to properly transfer heat and offer protection to the moving parts of the engine. However, regardless of how “watery” an engine oil becomes, it doesn’t become flammable or easily catch fire.

How Do You Store Oil So That You Don’t Expose It to Fire?

To store oil so you don’t expose it to fire, make sure it is in a well-ventilated area and take measures to contain spillage in case the oil spills. Be sure to keep the oil away from potential sources of fire because most fires are hotter than 400 degrees Fahrenheit.

– Keep the Oil in a Well-ventilated Storage Facility

Keep your container of motor oil exposed to the air as much as possible to prevent vapor build-up that could prove to be dangerous. Avoid packing other flammable items like diesel fuel near or on top of it.

If you’re storing big containers or barrels of motor oil, then take this more seriously. Clear the area around the barrels and always keep the windows open for enough air to enter the storage area.

– Take Oil Spill Containment Steps

Take measures to contain the oil in case it leaks, which is especially dangerous when other flammable materials are around. If you have a single small container of oil, it is better to keep it in a bucket of sand so that the sand will contain the spill when it leaks. However, if you have big containers or barrels of oil, then contact oil professionals for help in storing them.

– Keep Them Away from Potential Fire Sources

Keeping the motor oils close to sources of fire is a recipe for disaster. This is because most fires have a temperature that exceeds 400 degrees Fahrenheit and can easily heat up oils to their flash points.

The recommended distance between engine oil and a fire source is 3 meters, but if you have enough space, you can increase the distance between the two. This way, you’re protected against fire outbreaks should the fire ignition sources accidentally ignite.

Frequently Asked Questions

– Is Cooking Oil Flammable When Exposed to Fire?

Yes, cooking oil is flammable when exposed to fire. Vegetable cooking oil has a flashpoint of 599 degrees Fahrenheit. This is because vegetable oils are designed to be less viscous and retain heat easily so that they can cook food quickly and without stress.

– Is Oil Flammable in Water Sources?

Yes, oil is flammable in water sources because the oil will burn on top of the water. Oil and water do not mix due to their different properties, so the oil will form droplets on top of the water and will burn if its heat gets to the flash point.

Is it Safe to Use Engine Oil in a Subaru with AT Oil Temp Issues?

Using engine oil in a Subaru with AT oil temp issues can be harmful. Subaru oil temperature: meaning and solution should be taken into consideration when dealing with this problem. Seek professional assistance to diagnose and address the underlying cause to ensure safe operation of your vehicle.


This article has looked at the flammability of engine or motor oils and how to store them. Here are our final thoughts on the issue:

  • Engine or motor oils are not flammable because they are a high flashpoint, which makes them difficult to burn.
  • They are also made of big molecules which are responsible for their strong molecular bonds that are not easily broken.
  • Though engine oils are not flammable, they are combustible because they can eventually burn when heated to their flashpoints.
  • To burn engine oils, they must be heated to around 400 degrees Fahrenheit, where they can produce enough vapors to burn.
  • Keep in mind that the liquids themselves don’t burn but it is the vapors they produce that burn, which is why they need to be heated to a certain degree.

Take note that synthetic oils are even less flammable because they are thicker and transfer heat easily, thus they keep engines cool and lubricate moving parts of the engine. To store engine or motor oils, keep them in a well-ventilated area, take spillage containment measures and keep them about 3 meters from sources of fire.

5/5 - (19 votes)
Ran When Parked