Is Transmission Fluid Flammable?

Transmission fluid is made from a base oil that is mixed with various additives. It is designed to work under extreme conditions and to retain its protective properties even at high temperatures. But does this make transmission fluid flammable? 

No transmission fluid is not flammable under normal conditions. However, it is combustible and will ignite when it is heated beyond its flash point, from 302 to 383 degrees Fahrenheit.

There are a number of different types of fluids in your vehicle, and nearly all of them (except for gasoline) are not explosive or flammable under normal operating conditions.

How Flammable Is Transmission Fluid?

Under normal working conditions inside of an automatic gearbox, transmission fluid is not dangerous to work with and will not catch fire easily by itself even at relatively high temperatures.

is transmission fluid flammable
Transmission fluid is designed to work under extreme conditions

Transmission fluid is one of the fluids in your car that has a high flash point. The flash point value of a substance is a measure of how flammable it is. 

The definition of a flash point of a material states that it is the minimum temperature at which its vapors ignite when in the presence of an ignition source.

This means that the flash point is the temperature at which the material can burn while fuelled by its own vapor present in the surrounding air.

The flash point is measured in degrees Celsius or Fahrenheit.

Even though transmission fluid has a high flash point, it can still catch fire under certain circumstances. There have been recorded incidents of transmission fluid causing a vehicle fire after an accident or because of a large, continuous leak. 

This type of fire usually starts if enough transmission fluid comes into contact with a hot surface such as an exhaust manifold. 

What Is The Flash Point Of Transmission Fluid?

The flash point of transmission fluid ranges from 302°F to 383°F. There are a number of different types of transmission fluid available, and the flash point can vary depending on the type of additives used.

Compared to some other common fluids in your vehicle, the flash point of transmission fluid is fairly high. 

Transmission fluid is described as being combustible rather than flammable. When materials are assessed for fire hazard risks, they are generally described as flammable if their flash point is less than 100°F. If their flash point is above 100°F then they are described as being combustible.

Here is a table listing the flash points of some common vehicle fluids.

Fluid Type Flash PointIs It A Fire Hazard?
1Petrol<70°FYes
2Diesel<125°FNo
3Engine Coolant<260°FNo
4Brake Fluid>210°FNo
5Transmission Fluid>300°FNo

Can Transmission Fluid Burn?

Yes, transmission fluid can burn, if it is ignited with a suitable ignition material or if it is overheated beyond its autoignition temperature.

Usually “burnt” transmission fluid is a symptom of a problem with the automatic transmission. In this case, the transmission fluid is actually overheating regularly and degrading rather than burning in the traditional sense.

If the amount of fluid in the transmission is too low, this can cause the transmission fluid to regularly overheat inside. Overheating is bad for the transmission and the fluid and will cause a degradation of the fluid and a burning smell when driving.

Transmission fluid can also burn and cause a fire outside of the transmission. It will burn easily if added to an existing fire or can catch fire and burn if it comes into contact with a hot surface such as a hot exhaust or engine block.

Can Transmission Fluid Autoignite?

Yes, just like any fluid in your vehicle, transmission fluid can autoignite if it reaches a certain temperature under certain conditions.

The autoignition temperature of a material is described as the lowest temperature at which it will spontaneously ignite without an ignition source.

Autoignition temperature is also referred to as the kindling point of the substance, and it will vary depending on factors such as the atmospheric pressure of the surrounding environment, humidity and altitude.

The high temperature is the reason for autoignition as it supplies the activation energy that is needed for combustion to occur.

The autoignition temperature of transmission fluid changes depending on its location and current environmental conditions. For example, the autoignition temperature of transmission fluid is 900°F on a heated catalytic converter whereas this drops considerably to below 600°F when measured inside a sealed heated container.