Any good mechanic or vehicle enthusiast will know just how important it is to understand all the components and chemicals that are needed to make a vehicle run.
It’s even more important to know exactly how to use them all safely and prevent accidents happening in an environment with lots of dangerous substances around.
Transmission fluid is an essential ingredient in vehicles with automatic transmissions as it is optimized for things like valve operation, brake band friction and torque converters.
Transmission fluid is considered to be a combustible liquid and is therefore not flammable. However, it can still catch fire and pose a threat to the safety of those using it under certain conditions.
In this article, we’ll be taking a look at what exactly transmission fluid is, whether it’s flammable and how it should be used safely.
What Is Transmission Fluid?
Modern transmission fluids always consist of a base oil, which is then combined with a number of additive chemicals that are used to improve the lubricating effects of the fluid.
There are a variety of different transmission fluids available to purchase from garages or online and different types of cars will require a different type of fluid. The most commonly used one is Dexron III/Mecron.
This is used for most automatic transmission Ford and General Motors vehicles, as well as a variety of other brands. Of course, you should always check the manual for your vehicle to determine what the right kind of transmission fluid is for you.
If you end up using the wrong type of fluid for your vehicle’s transmission, it could do irreversible damage.
As well as causing poor lubrication in the transmission system, it can make the components overheat to a dangerous level and eventually cause the transmission to fail altogether.
Even the best mechanics might not be able to fix the transmission if the wrong fluid is used so make sure you triple check that you have the right one before using it in your vehicle!
A flash point is basically the temperature at which a substance can ignite in air and cause a fire. Interestingly, with most chemicals, it isn’t the liquid itself that can catch fire, but rather the vapors that are produced by it.
For example, a lot of high proof alcohols (anything with an alcohol by volume level over 50%) will produce enough vapors to ignite in the presence of an open flame or spark.
By definition, a flammable liquid is one that has a flash point under 100°F, whereas a liquid with a flash point over 100°F is known as combustible. As you might expect, the lower the flash point of a liquid is, the more easily it will ignite in air.
Of course, this means that both flammable and combustible liquids will produce enough vapor to ignite in air and burn extremely rapidly.
The difference is that flammable liquids can do so more easily and should be treated with significantly more safety precautions regarding open flames and sparks than a combustible one.
Hazard classifications for flammable liquids also take boiling points into account. Chemicals like petroleum ether have a flash point below 73°F and a boiling point below 100°F, making it one of the most hazardous flammable chemicals around.
However, something like p-xylene has a flash point between 73°F and 100°F, as well as a very high boiling point, meaning it is still a hazardous flammable chemical, but does not require as many restrictions to be sold.
Why Is Transmission Fluid Not Flammable?
As we’ve just established, a liquid is only considered flammable if it has a flash point below 100°F. The flash point of transmission fluid has a wide range but it can be as high as 383°F, putting it well above the point of being considered flammable.
This is a very important property for a vehicular chemical to have, as the temperatures inside a vehicle can often get very high. In fact, the internal temperature of an engine and transmission system is often around 195°F, which is almost hot enough to boil water!
This means that when a vehicle is running normally, it will not get hot enough to cause the transmission fluid inside to ignite and start a dangerous fire in the transmission system or engine.
Similarly, the boiling point of transmission fluid is even higher, at around 600°F, meaning there is no risk of the liquid boiling, as it would ignite into flame first.
Can Transmission Fluid Still Catch Fire?
So this all means that transmission fluid is definitively a combustible liquid, not a flammable one. However, this doesn’t mean it’s impossible for it to catch fire.
If the transmission fluid is in an environment where its temperature could exceed 383°F, its vapor will still ignite in air and burn extremely rapidly.
The only thing is, that temperature should never be exceeded under normal working conditions, such as in a tank at a garage or even in a normal transmission system of a vehicle.
The only danger that transmission fluid would pose of igniting is if it was introduced to an open flame or spark. For example, a flame from a match can be as hot as 1,100°F-1,400°F, making it hot enough to ignite the vapors emitted by the fluid.
Therefore, while this might seem obvious, you should always keep transmission fluid away from open flames and sparks!
How To Store And Use Transmission Fluid Safely
In a lot of workshops and garages, flames and sparks are pretty unavoidable, depending on the types of projects being worked on. However, there are still a few safety guidelines that should be followed when transmission fluid is present.
First and foremost, you should always keep the fluid enclosed in its container. The containers that transmission fluid is sold in are always designed to resist heat from sparks and brushes with flames.
This doesn’t mean that they are completely fireproof so it won’t be safe if left over an open flame for a while. However, as long as you keep the lid on the container, there is very little chance of the transmission fluid accidentally igniting.
You obviously can’t keep the fluid inside its container all the time, otherwise it would be useless! Whenever you do need to pour some into your vehicle for use, you should make sure your working area is kept well away from anyone else working with flames or sparks.
Sparks are considerably more common in a typical garage or workshop, especially if those around you are cutting metallic objects for vehicles.
To keep yourself and everyone around you safe, you should only be using the transmission fluid when everyone in your vicinity has stopped creating sparks.
Frequently Asked Questions
Is It Safe To Burn Transmission Fluid?
In some instances, you can actually burn transmission fluid safely. It is a pretty good fuel to use in furnaces because it has a BTU value, meaning it will burn efficiently, and it won’t produce harmful fumes when you do.
This is why burning leftover transmission fluid is a good way to recycle it rather than having to throw it away.
What Car Liquids Are Flammable?
We’ve already established that transmission fluid is not flammable and this is also the case for most of the liquids you’d use in a car. In fact, pretty much the only flammable car liquid is gasoline, which has a flash point of roughly -45°F.
Because this flash point is below 100°F, it is considered flammable, but every other liquid you’d use in a car has a higher flash point than this, and is therefore combustible.
This includes brake fluid, power steering fluid, engine oil/motor oil, windshield washer fluid, and refrigerants/lubricants.
Hopefully, you now know a lot more about the fire risks associated with transmission fluid. While it isn’t technically flammable, there is still a risk of it catching fire if introduced to an ignition source like open flames and sparks.
However, if you follow the safety steps we’ve outlined in this article, you’ll have no problems using transmission fluid safely with your vehicle.