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The Truth About Motor Oil and Flammability

  • Cars Explained
  • Silas Smith
  • 4 minutes

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The engine oil on your car is one of the most important components of your car that helps in its smooth operation. You cannot even think about driving without oil on your car as it leads to wear and tear on the engine components and causes irreparable damage. However, the question of whether motor oils are flammable might’ve crossed your mind at least once. Do they pose a fire hazard if a spark hits them unexpectedly? We’ll find all the answers to all these concerns in this article.  

Is motor oil flammable? 

It might surprise you to know that motor oil is not flammable. It is only combustible. To understand this clearly, let us take a look at the definition of a flammable liquid. The Occupational Safety and Health Administration (OSHA) has defined a flammable liquid as one which ignites between the temperature range of 149-200 Fahrenheit. While a combustible liquid is one that ignites at or above 200 Fahrenheit. Motor oils need about 300-400 F (150-205 degrees Celsius) to burn, putting them in the category of combustible fluids.

is motor oil flammable  

So, you don’t have to worry if the motor oil on your car will burst into flames when exposed to a small amount of spark. However, it is definitely a matter of huge concern if your engine temperature is increasing due to a dip in oil levels. This results in a high temperature capable of combusting the motor oil.  

Why are motor oils non-flammable? 

Motor oils or any other flammable liquid, for that matter, has short chains of hydrocarbons. These hydrocarbons release vapor, allowing them to be flammable at comparatively lower temperatures. Weak intermolecular forces are those which facilitate the easy release of vapor. So, in the case of highly flammable goods, these bonds can break with lesser energy.  

However, engine oils being heavier liquids, have stronger intermolecular forces, requiring higher energy to break and thereby combust. This is the reason why they require way higher temperatures to break down.  

Normal operating temperature range of a car engine 

The normal operating temperature range of a vehicle engine is around 195 to 220 degrees Fahrenheit. However, this again depends on the make and model of your car. Components of the cooling system, such as the thermostat, radiator, and water pump, ensure that this temperature range is maintained throughout.  


At what temperatures are motor oils flammable? 

Before knowing more about the flammability of motor oils, it is essential to understand the concept of flashpoints. Flashpoints are those temperatures at which a fluid gives off enough vapor to make them ignite. Motor oils have a very high flashpoint of 300-400 Fahrenheit, which makes of one of the least flammable fluids.  

Are synthetic motor oils flammable? 

No. Synthetic motor oils, in fact, are less flammable when compared to regular motor oils. They are formulated in a way that has better temperature resistance. However, they have a flashpoint they’ll break down upon reaching. These can range from about 450F and can go as high as 700F for some specialist synthetic oils.  

Are silicone oils flammable? 

Silicone oils, which are used in hydraulic systems, are highly temperature stable. They are not flammable and are good electrical insulators.  


Now that you’ve read this article from top to bottom, we believe you know why motor oils are not flammable. Technically, you cannot say that they’re not flammable, as they can break down at much higher temperatures. It’s the OSHA definition that puts these terms apart. However, the fact that they require higher temperatures to combust should let you shy away from addressing problems like oil leaks, which result in a high-temperature build-up, rendering your car inoperable.  

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