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Brake fluid: replacement and selection

When and why it is necessary to replace brake fluid

As a rule, brake fluid replacement term is noted in the car operation manual and on the average is 1-3 years. Periodicity of replacement greatly depends on vehicle operation conditions and driving style. Unscheduled replacement of brake fluid can be necessary at its soiling. Also new product is filled after removal of brake system elements, for instance, after installation of new hoses.

The cause of unit defects can be, in particular, improper installation of the brake pipes during repair or replacement. And fluid soiling is usually the result of oxidation and wear-out of various brake system parts.

Most of all, loss of operational properties of brake fluid is indicated by long travel of the brake pedal and worsening of braking efficiency. In case of working liquid leakage due to damaging of the hoses or reservoir, the corresponding indicator will be lit on the dashboard. Moreover, traces of brake fluid can be noticeable, for example, under the bonnet or on the wheels.

It is recommended to replace working fluid at a service station. This product is toxic, so its replacement should be performed following all the safety precautions. After the procedure it is necessary to perform air bleeding of the brake system in accordance with the recommendations, noted in the car technical documentation.

How to select brake fluid

According to contents there are three types of fluid: mineral, glycol and silicon. The mineral one is based on castor oil and alcohol (for example, butyl one) and has good anticorrosive characteristics.

Glycol fluid, created on the basis of polyglycols and their ethers, possesses excellent parameters of viscosity and good lubricating qualities. The disadvantage of this production is high hygroscopic property.

Silicon brake fluid is made of organosilicone polymeric products. The main advantage of such compounds is absence of hygroscopicity, the disadvantage – poor greasing qualities.

Proper operation of the brake system is of highest importance for safe exploitation of the car, that is why, special requirements are claimed for brake fluid quality. In order to be sure of product characteristics, give preference to products of reliable manufacturers, such as Bosch, ATE, A.B.S., TRW, Valeo, Ferodo.

During selection of brake fluid be guided by recommendations of the car manufacturer. Purchase the product in accordance with the car brand and model, type of the brakes.

Pay attention to classes of working fluid: DOT3, DOT4, DOT5, DOT5.1. According to the class the products differ from one another by boiling temperature, viscosity grade, and features of rubber and metal influence. During selection you also need to consider, if ABS is installed in your car: there are special fluids designated for this system.