As long as your brakes function properly, how often do you really think about your car’s brake fluid? Brake fluid is unfortunately often forgotten about. There are service items and maintenance tasks we constantly check and do every few months, but we should not forget about this important fluid.
In this article, we will cover the basic things you need to know about your brake fluid, and how to change your brake fluid by yourself. Note that this is not a complete flush – you need two people for that job, but fortunately, a complete flush is rarely required (or even done by dealerships while we’re at it, so don’t stress).
How often should you replace your brake fluid?
Most car manuals and people will tell you to change your brake fluid every two years, or 30,000 miles (about 50,000 km). But most manufacturers who use a mineral oil-based brake fluid typically suggest you flush it and refill it with fresh brake fluid every three years.
For some cars, you won’t even get a factory recommendation since they know it will likely be fine for the length or the loan or lease, so they call it ‘lifetime’.
Because replacing brake fluid takes only a couple of minutes and you can do this by yourself and the fact that the brake fluid is an important part of your car’s braking system, I recommend you do the operation explained in this article every year. Especially if you love driving aggressively or you find yourself towing a trailer or something often.
How can you tell if you need to change your brake fluid?
I’m going to sound like a broken record, but if you know it has not been changed in the last two years, change it. Do it as soon as you can.
Brake fluid does not last forever. Dealership ‘lifetime’ refers to the lifetime of the lease, as they want/hope you’ll get the new model once your lease ends. Brake fluid degrades over time and between heat and moisture, it can even cause internal corrosion. We don’t want that.
Your brake fluid should always be clear. If it has any trace of darkness or murkiness, or smells burned, it needs to be replaced.
Why does brake fluid go bad?
Brake fluid is hygroscopic – that means it absorbs moisture from the air. And as moisture builds up in the fluid, it is more prone to overheating and fading. The older your brake fluid is, the less effective it will become. That’s just the way it is. Thank god it’s cheap!
Apart from the above problems with overheating and fading, moisture corrodes your calipers, wheel cylinders, brake lines, and everything else. And because it’s working from the inside out, we really want to prevent this from happening.
If you run your car hard (maybe you hit the race track once in a while) or even tow heavy loads, the brake fluid can get too hot and boil. Overheating degrades the brake fluid’s viscosity and effectiveness. So if the fluid in the master cylinder (the brake fluid reservoir found under the hood) smells burned or it is really dark. Do consider changing it as soon as possible.
What type of brake fluid do I need?
Apart from checking the manual, you can just check most auto parts online shops that let you choose your car’s manufacturer and model. Or just use a manufacturer’s website!
Motul has great products. And fortunately, their website even has a step selector for all the fluids they make, even brake fluids. (check it out here – I am not sponsored or anything. It’s just easy to use!)
Usually, if you find that your car needs DOT 3, DOT 4 or DOT 5.1 fluid, keep in mind that they can be mixed. But just get the highest quality one you can afford/get your hands on. There’s no reason to put something inferior in your car.
Be careful! If your car uses DOT 5 that does not mix with anything else. It is mineral and should be replaced with DOT 5 brake fluid. The same goes for all mineral brake fluids.
The main difference between various types of brake fluid is the minimum boiling point, with DOT 5.1 having the best characteristics. That’s not to say that there are not some premium DOT 4 brake fluids that outperform the DOT 5.1 standard, but just by buying DOT 5.1 brake fluid, you can ensure that you have the good stuff in your car, and you really shouldn’t stress more about this if you’re not competitively racing or something.
How to replace brake fluid by yourself
Let’s go through the steps needed to replace the brake fluid by yourself. This will not be a complete flush, as that is rarely needed. And because most dealerships will do the exact same thing every two years or if you ask them (or dumbly say it’s lifetime. Again, brake fluid does not last a lifetime!!), you can save a lot of money or even get a safer car by DIY-ing this operation.
You’ll need some stuff for this maintenance task:
- new brake fluid;
- disposable gloves
- a turkey baster (and write on it. It’s whole life it will only be used to change brake fluids);
- lint-free cloth;
- some old rags;
- a container that can securely hold the old brake fluid;
Park your car on a level surface and let it cool down
Like the title says, park the car on a level surface and let it cool down for a couple of hours. It’s just easier.
Clean the brake fluid container at the master cylinder
We don’t want to introduce dirt into the braking system. Put your gloves on. Now carefully and properly clean the cap, the liquid container, and the area around. Use a lint free-cloth to make sure you can do a good job.
Cover some stuff around with some old rags
I like to cover the area around with old rags or something just in case I accidentally drop some old or new brake fluid somewhere. I even cover the fender from the side I work on.
Brake fluid absolutely destroys paint. So make sure to cover everything well. Better safe than sorry!
Get the old brake fluid out
Now take the turkey baster and get as much of the old brake fluid as you can, and put it in an empty bottle or container.
Try not to touch the rubber part of the turkey baster with brake fluid. That will help it last longer, as brake fluid is not friendly to rubber parts.
Put the new stuff in
Fill up the container with fresh brake fluid, to the MAX line. And screw back the cap.
You’re done! Take out the rugs, and close the hood. Clean the turkey baster with some water (if you’re lucky, it will last for a while, and you can use it again the next time you need to change your brake fluid).
You’re all done.
Now make sure to dispose of the old brake fluid according to your state’s laws! That stuff is highly toxic.
Wrapping it up
You need your car to brake efficiently. So don’t neglect this easy part – the brake fluid. Keep a scedule yourself to make sure you change it at least every two years or if the mileage mentioned in the article is reached.