Some people suggest putting transmission fluid in the brake system. Although both are vital fluids for your vehicle, you might want to ask yourself if this is wise advice because transmission fluid and brake fluid are different substances. So, is this solid advice or just another bit of misinformation?
You cannot use transmission fluid as brake fluid because doing that will damage key components in the braking system. Brake fluid and transmission fluid are entirely different liquids, each with unique properties suited to its specific role in your car.
Keep reading to learn why you should never use transmission fluid in the braking system. You will also find out what you can do in an emergency and the realistic alternatives to brake fluid. Let’s dive in.
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Why You Can’t Use Transmission Fluid for Brake Fluid
Hygroscopic fluids such as brake fluid absorb moisture to help avoid rust in the calipers. Transmission fluid is not a hygroscopic fluid. It is a petroleum-based fluid, and petroleum and diesel-based fluids can destroy brake pads because they react to an undesirable effect with rubber components.
It can be expensive to replace the parts damaged using transmission fluid here. In fact, vehicles can be written off when using non-hygroscopic fluids like transmission or power-steering fluid instead of brake fluid.
The Purposes of Transmission Fluid and Brake Fluid
Transmission is the movement of power to a vehicle’s axel from the engine. This process is aided by transmission fluid, whose purpose is to lubricate, cool, and prevent oxidation, among other things.
On the other hand, brake fluid helps components in the brake system stop the vehicle when you hit the brakes. It also acts as a lubricant.
Transmission Fluid And Brake Fluid: The Differences
These two essential fluids have some fundamental differences. They must be kept apart, labeled clearly, and definitely not used interchangeably for any reason. The only similarity between brake and transmission fluids is that they are both liquids.
While traditional transmission fluid is made from crude oil, synthetic transmission oil is created through chemical reactions. On the other hand, brake fluid is usually glycol-ether-based, making it a very different liquid.
What to Do When You Put Transmission Fluid in the Brake System
A professional must take a look at it. Do not attempt to drive your car to the garage. Seek professional help and get the system flushed and parts replaced as soon as possible. You might be able to salvage something, but vital components will likely need to be replaced.
It is imperative that repairing and replacing are not taken lightly. No expense should be spared because driving the car after this costly mistake can be life-threatening. As mentioned earlier, it may even be that your vehicle is totaled, which needs to be taken on the chin with expensive lessons learned.
What Can Be Damaged by Adding Transmission Fluid to the Brake System?
Adding transmission fluid can seriously damage many components. Replacing these parts can often result in costs exceeding the car’s value. Therefore, insurance companies sometimes write off the vehicle instead.
Adding transmission fluid to the brake system can damage the following braking system components:
- The anti-lock brake module
- The master cylinder
- The proportioning valve
- The rubber hose connectors
- The calipers
- The wheel cylinders
Evidently, swapping out brake fluid for transmission fluid affects enough components to cause brake failure or even render the vehicle unroadworthy.
How to Know When To Change Your Brake Fluid
Several indicators show it’s time to change your brake fluid. The telltale signs include:
- The brake fluid is not clear.
- The anti-lock braking system (ABS) light is on.
- The smell of burning rubber.
- A new noticeable softness or springiness in the brake pedal.
- The brake fluid is below the brake-fluid-level line.
- Brake performance is not as it was before.
- Complete brake failure.
Complete brake failure is, of course, the biggest one to worry about here. However, regular checking and maintenance can help avoid this. Brake fluid testers are an economical and easy way to give you peace of mind if you are in doubt.
These well-reviewed Phoenix Systems Coolant + Brake Fluid Double-Ended Test Strips are available on Amazon and provide a satisfying option for drivers. With this kit, you’ll be able to identify brake fluid problems before they become significant enough to cause breakdowns and necessitate costly repairs.
What Can I Use for Emergency Brake Fluid?
You can use soapy water and water from the radiator as brake fluid in emergencies. While neither is efficient as conventional brake fluid, both alternatives are safer and easier on the brake system component than transmission fluid.
Let’s take a closer look at both alternatives, as well as an unorthodox braking method you can use when you’re stranded in the middle of nowhere.
Soapy Water
Soapy water can be an emergency form of brake fluid. It is easy to make, and it won’t corrode the system if you don’t leave it in there for too long.
Use the brakes sparingly when using soap and water in the brake system. Braking causes the water to boil, so this will happen quicker if braking consistently. Go easy on the brakes and keep the speed at a minimum.
Water From the Radiator
If you are in a real fix and soap and water are not available, you can use the water from your radiator. However, you’ll want to ensure your brakes take ample cooling stops if you’re a long way back home.
Keep in mind that using soapy water or radiator water is for emergency use only. When you are out of brake fluid, the safest thing to do is walk or use public transport and leave your vehicle in the driveway.
Engine Braking
Engine braking is the unorthodox method I was referring to earlier, and it’s worth a try if you have no other option. While it doesn’t work well on its own, it can be a great compliment to the above brake fluid alternatives.
Engine braking is the process of working down the gears as you take the pressure off the accelerator. This YouTube video will give you a more in-depth look at how to engine brake effectively:
This technique can be a little difficult to master, but it does limit the impact on your brake system. It helps limit the need for using the brakes, which goes a long way to prevent your soapy or radiator water brake fluid from boiling.
Is It Common for People To Use the Wrong Fluids in Their Car?
It is much more common than you think. People have passed on the wrong information about many things since the beginning of time. Once that information goes viral, it can be tough to correct.
However, we live in a time when we are just a click away from almost any information we require in our daily lives. If you are not confident about anything related to your car, avoid the heresy and consult an expert or find some reliable information online.
How To Avoid Accidentally Using the Wrong Fluid
Everyone has a system for storing such things as fluids for their cars. However, one thing that makes absolutely no sense is keeping them stored next to each other. Even the most car-knowledgeable person could absent-mindedly pick up the wrong container in this situation.
Keep car fluids separate and ensure the labels are clear and easy to read. You should replace any labels that have worn away with clearly-written homemade ones.
Final Thoughts
Rumors spread much more quickly than they used to, thanks to the invention of the internet. False information can go viral as fast as accurate information can.
However, the resources to find the truth are just a click away. With a common-sense filter, most of us can easily find accurate information.
The myth that transmission fluid is a suitable replacement for brake fluid is one such piece of information that needs eradicating immediately. Now that you have found the correct information, how about sharing this post to make sure everybody else is aware?