It may not cross your mind every time you stop your car, but it’s brake fluid that gets the job done for you.
Proper care of brake fluid is one of the most important maintenance and safety factors in the upkeep of any vehicle.
Many people don’t know much about brake fluid, and it can be a little bit intimidating.
However, it only requires a little basic knowledge to understand the job your brake fluid does. You also need to know the special precautions you should take with it. And also know the correct fluid for your car.
What Brake Fluid Does
Brake fluid is what’s called a “hydraulic fluid.” Most people have heard the term “hydraulic” before, but many don’t know exactly what it means.
It means moved or powered by fluids.
That’s exactly what brake fluid does: it moves components in your vehicle’s braking system.
Brake fluid is special because the job it does is especially hard.
It has to work perfectly under high pressures and temperatures.
That’s why it’s so important to maintain your brake fluid under good repair because as it ages it doesn’t work as effectively.
Brake Fluid and Moisture
It’s necessary to flush and replace your brake fluid periodically, because brake fluid is hygroscopic, meaning it readily absorbs moisture.
That means that you should always take special care to protect your brake fluid from contact with water, especially when topping off the fluid.
Brake fluid will even pull moisture in directly from the air.
Over time brake fluid becomes too saturated with excess moisture, which causes it is degrading.
Once moisture content reaches a certain level the brake fluid is no longer able to function properly in the brake hydraulic systems.
The DOT Ratings
One of the most common questions people have about brake fluid concerns the DOT ratings.
Here are a couple of common questions.
What do the DOT ratings mean?
- The DOT stands for Department of Transportation
- The DOT has placed regulations concerning the acceptable specifications for brake fluid to be used in automobiles in the US
- This is to assure a uniform quality of a product for everyone’s safety
- The biggest factor in the different DOT ratings is resistance to the effects of heat and moisture
Can different DOT rated fluids be mixed? Yes and no
- Any two DOT rated fluids can be mixed without causing a harmful condition (Cross-compatibility is one of the requirements of the DOT rating)
- However, it isn’t recommended. It’s important to take the utmost care in maintaining your braking system, so there’s no reason to cut corners on something like mixing fluid
Is a higher rating better? Not necessarily
- DOT brake fluids are backwards compatible meaning that each new release meets or exceeds the specifications for the previous grade
- What that means is that you can put DOT 5 fluid in a DOT 3 braking system, but you should never put DOT 3 fluid in a DOT 5 system
What is the right DOT rating for my car?
- The appropriate brake fluid for your car is decided by several factors including the age of your car, its size and whether it is equipped with ABS or traction control
- The easiest way to be sure what type of fluid your car needs is to check your owner’s manual