Brake Fluid Change Interval Car Vs Motorcycle
Why is it important that brake fluid is in good condition? Even though fluid dwells in a sealed system, it still can absorb moisture over time, and that absorption can lead to corrosion in the brake system and brake lines. Moisture also lowers the boiling point of the fluid, and that can reduce a vehicle’s brake pedal effectiveness in repeated hard stops, or it could even lead to brake failure.
If the manufacturer lists a 10-year interval or none at all for replacing brake fluid, why do you need to have your brake fluid flushed, and how often should a fluid flush be done?
Unless the manufacturer calls for it sooner, monitor your braking performance to see when you are due for a flush – and while you’re at it – have old fluid replaced at the same time as other brake component work, such as replacing brake pads, callipers or discs. Replacing brake fluid is cheaper than replacing brake lines or a master cylinder that has corroded, so don’t automatically dismiss the brake recommendation of a mechanic as just salesmanship.
And no matter who suggests fresh fluid, make sure the brake fluid replacement is done with the type that is called for by the vehicle manufacturer. Some vehicles require DOT 3 fluid, others a different variety, such as DOT 5 fluid, so consult your owner’s manual before you give the go ahead.
How Often is Brake Fluid Changed on a Car?
As a general rule, it is recommended to change the brake fluid once a year or every two years. Of course, this also depends strongly on the way of driving and the mileage.
The reason for this measure is that brake fluid is very hydrophilic, that means it tends to absorb water. When applying the brake, the braking system, and with it the brake fluid, is heated up in such a way that the water starts to boil and form vapour bubbles. These bubbles are compressed during braking. Therefore, the increasing proportion of water in the system reduces the brake pressure. The specialist garage is able to determine the boiling point of the brake fluid and thus state when it became necessary to change it.
If you are in doubt, better change the brake fluid once too often which is good for safety.
How Often is Brake Fluid Changed on a Motorcycle?
For road use, it is recommended that your brake fluid be change every 1-2 years. This would more than likely be completed as part of your service schedule.
On the track however you do not want to have any chance of experiencing any kind of performance drops given the level at which you rely on the brakes, so changing it earlier wouldn’t be a terrible idea. Around once a year if not more if you do quite a lot of track days.
People will comment it should be changed a lot more often because it experiences a lot more heat, but when buying the best fluids from the best brands you shouldn’t experience any performance drops due to overheating.
What Types of Brake Fluid Are Out There?
The three main types of brake fluid now available are DOT3, DOT4 and DOT5. DOT3 and DOT4 are glycol-based fluids, and DOT5 is silicon-based. The main difference is that DOT3 and DOT4 absorb water, while DOT5 doesn’t.
One of the important characteristics of brake fluid is its boiling point. Hydraulic systems rely on an incompressible fluid to transmit force. Liquids are generally incompressible while gases are compressible. If the brake fluid boils (becomes a gas), it will lose most of its ability to transmit force. This may partially or completely disable the brakes. To make matters worse, the only time you are likely to boil your brake fluid is during a period of prolonged braking, such a drive down a mountain — certainly not the best time for brake failure!
Cover Image Credit: Scrap Car Network