What’s the Point of Brake Fluid?

The quality of brake fluid affects the reliability of the braking system and road safety.  This substance transmits energy from master brake cylinder to wheel cylinder.

Vehicle braking is characterized by friction forces between the brake rotor and brake pads.  This releases a certain amount of heat which is transmitted to brake fluid through service elements of the brake system.  Therefore, boiling point and viscosity are very important parameters of this substance.

Besides, it must meet a number of other requirements:

  • Minimal impact on the rubber parts of the brake system.
  • Good corrosion resistance.
  • Good lubricating properties.
  • Stable operating properties at low and high temperatures.

The composition of brake fluids

Mineral brake fluid is composed of alcohol and castor oil.  They do not meet current standards regarding boiling point and viscosity index.

The composition of glycol brake fluids include polyglycols and their esters.  These fluids have a high boiling point and good viscosity.  At the same time, they possess a significant disadvantage, because they can absorb moisture from the atmosphere.

Silicone brake fluids are produced from silicon-organic polymers.  Their positive properties include: a wide range of operating temperatures, low hygroscopicity and inertness to various materials.  Their main drawback is low lubricity.

Mixing of brake fluids

You can still find two alternative views as to whether it is possible to mix brake fluid or not.  The answer is both yes and no.  The point is that mixing is allowed only when both liquids have the same basis.  Such information can usually be found on product label.  If for any reason there is no label, it is better not to take the risk.  Before mixing it is also necessary to evaluate the operating temperature of the fluid.

It is also worth mentioning that silicone brake fluid cannot be combined with fluids with a different basis, as well as mineral fluid cannot be mixed with glycol-based fluid.



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