Brake fluid replacement is one of those things we tend to forget about when servicing our cars. While no one sane would omit regular change of engine oil, filters or brake pads, things are quite different for the contents of this hydraulic system.

Brake fluid acts as an amplifier of your foot force when you step on the brake pedal. Created pressure causes brakes to slow down or stop a moving vehicle. Ageing brake fluid causes the whole system to be less and less reliable, resulting in significant danger to the drivers, passengers and other people on the roads.

To be on the safe side, you should replace your brake fluid more or less every two years. You can do it yourself to save some money or go to a garage to have it done for you. We strongly recommend choosing the latter option. Unless you are a professional, brake fluid change will take a lot of time and might be quite stressful. If, on the other hand, you prefer to look after your vehicle yourself, remember to buy quality fluid, get your tools ready and follow these simple steps.

Changing brake fluid yourself

Measuring the brake fluid of the car.

Before you start, note that brake fluid is very corrosive. If it dips on any metal surface, fluid will commence eating through it unless you wipe it off immediately. Remember that the reservoir is usually next to the engine. So when you are topping it off, pay extra attention.

  1. Use a baster to empty the reservoir. Remember to put it in a vessel and take it to the recycling point, never ever pour it down the drain.
  2. Clean the reservoir with a cloth.
  3. Refill with new brake fluid until the surface is close to the 'max' line on the reservoir.

This method doesn't really replace all the brake fluid. There is still some left in the callipers or wheel cylinders, and to drain it, you would need a jack and a helper. It is also very easy to suck some air into the system during a complete flush and refill. It is something you have to avoid, so better leave it to the professionals.

Check for water in the brake fluid

You should definitely replace fluid if it has some water in it. The best way to assess the level of water present in the brake fluid is to use a dedicated tester. These come in two forms, a pen and stripes. The way they work is exactly the same. You dip them in the fluid, and the result shows on a scale, the more water, the more urgent the replacement

More expensive tests can also detect and measure corrosion in the ABS (Anti-lock Braking System) by identifying suspended copper ions. It is generally unnecessary in the case of younger cars, but if it's been a while since your four wheels left the production line, testing is a good idea.

What brake fluid should I choose?

Brake fluid is being replaced.

When going shopping, remember that there are different kinds of brake fluid. They are classed from DOT1 to DOT6, with the former being low-quality and the latter a high-end type. It is a good idea to spend your money on the best product available. DOT6-class brake fluids don’t eat paint and are non-hygroscopic, meaning that theoretically, they will not absorb moisture. In reality, they ingest less water and more slowly, but still, it is better to use those than to save a few quid on a less reliable product. Take note that there are special fluids for cars equipped with an ESP system.

How much does it cost to replace brake fluid?

Even though brake fluid change is a pretty simple procedure, it is time-consuming and could prove a challenge to a first-timer. If you are unsure of your skills or simply can't spend between an hour and two hours, go to your trusted garage. A professional mechanic will only charge you about £60-70 for this job (much more if you choose a dealership), including cleaning pipes with a brake flushing machine, and will also give you a warranty, something you can never have when doing this on your own. The brake fluid itself costs only between £5 and £15, depending on the quality and volume.

When should you change your brake fluid?

a mechanic is screwing on the cap of the brake fluid container.

When is the best time to change brake fluid? Common sense dictates that it is when you are also changing your brake callipers, pads or rotors. It is much easier, takes a lot less work and hassle.

Your safety on the road, as well as the safety of other people, depends on your ability to slow down or stop whenever needed. To be able to do that, remember about your brake fluid. Replace it with a new one regularly and only choose quality products to avoid disappointment and danger.