Every system in your car is important to how it operates but you can make a good argument that once your car is running, nothing is more important than the brakes. Brakes are the crucial safety feature that keeps both you and others around you safe as much as possible. No one would ever willingly drive a car that doesn't have brakes so you need to take care of them as best you can.
Your brakes are a hydraulic system which means the pressure of brake fluid in your brake lines is what allows them to function. When you put your foot on the brake pedal, the pressure in your brake lines causes the calipers to squeeze down on your brake pads which in turn creates the friction required to slow your wheels down and stop the car.
The pressure of your foot on the brake pedal causes a piston inside the brake master cylinder to push down and compress that brake fluid through the pipes and hoses of your brake system. If you don't have enough brake fluid in the line, that pressure is compromised, and your brakes are not responsive as a result. Likewise, if there's a problem with your brake fluid such as rust or contamination it may not work properly as well.
Brake fluid is known as a hygroscopic liquid which means it can absorb water. The more water and moisture that your brake fluid absorbs overtime, the lower the boiling point gets. That's important because the lower the boiling point the less effective it is going to be since your brakes generate a lot of heat. You'll need to replace the brake fluid as part of routine maintenance in order to get fresh fluid back in place that has a higher boiling point.
It's worth noting that there are several kinds of brake fluid available including silicon-based fluid which is actually not hygroscopic and will not absorb water at all. However, not every vehicle is designed to work with this kind of brake fluid, which is known as DOT 5 brake fluid. You absolutely cannot mix this kind of brake fluid where the kind that can absorb water as it will effectively destroy your brakes. For that reason, you need to know what kind of fluid you have in your lines before you replace it.
How Often Do Brakes Need to be Flushed?
As a general rule, you need to replace your brake fluid in order to avoid that moisture build-up. This is true for DOT3, DOT4 and DOT5.1 brake fluid. Those are all the hygroscopic kinds that your car can use and those are the ones that absorb moisture.
Depending on the kind of brake fluid that you have and the kind of car you're driving the time frame for changing your brake fluid can vary significantly. For instance, Honda recommends that you change your brake fluid every three years, regardless of how many miles you've driven in the vehicle. On the other hand, Chevrolet recommends changing brake fluid every 45,000 miles. Mercedes-Benz says every 20,000 miles. As you can see it's really a mixed bag. Your best bet is to check with your owner's manual.
There's a general rule of thumb that you should go every 30,000 miles, but as you can see that can be pretty inconsistent and if you're really interested in preserving the life of your brakes you should consult the owner's manual rather than go by averages or guesses that can apply to any number of different vehicles across the board. When in doubt, always check with your owner's manual.
Obviously not every driver is going to be conducting routine inspections and weekly maintenance on their vehicle. While some people are fanatical about maintaining every system of their vehicle like clockwork, many of us tend to let things slide because we forget about them and it only comes up when we realize something has gone wrong. You should definitely be doing your best to make sure you get your brakes checked at least every couple of years however. If it's been more than three years since you had your brakes inspected, then you absolutely want to get to a mechanic as soon as you can to have them checked out. As we said, this is an extremely important system in your vehicle that preserves not just your safety but the safety of everyone around you. Don't let this slide for too long.
How Much Does It Cost to Flush Brake Fluid?
When you head to a mechanic to get your brake fluid flushed, you can expect to end up paying somewhere in the neighbourhood of $80 to $150 to get this job done. Most of that cost is going to go towards labor so the range really depends on in some small part the make and model of your vehicle, but more often it relates to the mechanic you take it to. No doubt if you call a few places in town you'll get different quotes for the same job.
To do a full flush of your brake fluid you need about 1 quart or 32 ounces of fluid to get the job done. If you head to Amazon, you can probably buy that much brake fluid for as little as about $15 up to around $50 depending on the kind of fluid you buy. So if you were going to handle this job on your own, the cost of materials that you're looking at is definitely not going to break the bank and will save you a few dollars versus heading to a mechanic to get the same job done. The only concern here is whether or not you have the time to get it done and you're confident in your ability to do home car maintenance.
Signs and Symptoms That You Need a Brake Fluid Flush
Obviously following your owners manual recommendations for when you need to flush your brakes is a good place to start but there are so many occasions when your car is going to let you know that you need to get your brake fluid checked as well. If you're experiencing any of these symptoms you should get your car to a mechanic as soon as you can to get it checked out.
Low Fluid Levels: Your vehicle has a brake fluid reservoir that you can have a quick visual inspection of to see how things are going. The location of this reservoir is not the same from one car to another but you will likely find it on the driver side of your engine somewhere near the firewall, which is the wall that separates your engine compartment from the cabin on your vehicle. If you're not one hundred percent sure you can Google your make and model or, again, check the owner's manual. Take a look at it and see where the levels are at. If they're low, then you know you need more fluid.
Dirty Brake Fluid: When you take a look at the fluid in the reservoir it's not just the level that you're looking for but the quality. If you have dirty looking brake fluid, something that looks a bit like old motor oil, then that means it's been heavily contaminated and will need to be flushed.
Leaks: This is a hard to identify symptom because you have several different fluids in your vehicle that could be leaking out at any given time. If you've noticed spots of brake fluid on the driveway however then obviously you have a problem with your brake lines that's going to need to be addressed sooner rather than later. Your brake lines contain numerous hoses and gaskets that could wear down and cause the system to leak so you'll need to get this identified as soon as you can.
Veering When You Stop: When you're driving and you put your foot on the brakes if you find your car pulls to one side or the other as a result, it's very possible that you're suffering from low brake fluid. This is caused by the pressure not being able to apply evenly across all of your brakes, so one brake will clamp down harder than another causing you to veer in that specific direction.
Can I Flush My Own Brake Fluid?
We mentioned earlier the cost of brake fluid alone is much cheaper than getting an entire flush done at a mechanic. That's true, but there is one issue with getting a brake fluid flush done at home. Doing this job is not easy depending on how you approach it. If you're not super familiar with doing a lot of home car repairs, and the most complicated thing you've ever done is change the tire or an oil filter, this could be a difficult job for you to handle on your own.
That said, there are some less than official ways of doing a brake fluid flush that involve turkey basters and empty drink bottles that you can handle on your own and are not entirely complicated. You can check out the method in a video like this one and see how to do it with another person or, in a pinch by yourself. Again, if you check out this video, you'll see this is definitely not how the dealer is going to do it if you take it in to get the job done professionally, but that doesn't mean it doesn't work. You need to decide for yourself if you want a repair job like this done strictly by the book or if a quick mechanic tip like this one is good enough for you.
If after checking out the requirements for getting a job like this done on your own you feel confident, then just make sure you're doing it as safely as you can. And make sure you wear gloves and safety equipment. You absolutely don't want to get brake fluid on your skin as it can be absorbed and cause damage to your kidneys.
What's a Good Substitute for Brake Fluid?
This is a question that gets asked occasionally on the internet and if you Google it you will find sites that offer you various answers. For instance, more than one website has recommended something like Castrol LHM plus fluid which is for power steering, or fork cartridge oil, or even mineral oil. These kinds of recommendations come on forums typically, not mechanic or automotive manufacturer websites by any means.
There is no substitute for brake fluid in your car. Maybe in a bicycle, in a pinch, but not a car. Never ever use anything but brake fluid as brake fluid in your car. The very idea that you would put your safety at risk to improvise a solution to a problem with your brakes is extremely irresponsible. No matter what you see on the internet, just don't do it.
The Bottom Line
Keeping good quality brake fluid in the correct quantities in your brake system is crucial to making sure you're as safe as you possibly can be behind the wheel of your car. You never want to skimp on brakes or your safety. It's just not worth it. Always make sure you're familiar with what your owner's manual says about when you need to have routine maintenance done. Everything from oil changes to transmission flushes to brake fluid flushes can change greatly from one vehicle to another. There are some great rules of thumb that you can go by to get an idea, but there's no substitute for making sure you know exactly what's going to be best for the make and model of car that you're driving.
Whether you opt to take your car into a mechanic to get the brake fluid flushed or if you think you can handle it on your own, just make sure you're sticking to a routine schedule and get it done before the situation gets so bad that your brakes end up failing on you and you get stuck with expensive repair bills for damages, or something even worse as a result of a serious accident.