Class of brake fluids

The fact that brake fluids are hygroscopic is at the time an advantage and a drawback…

AN ADVANTAGE,

because water is everywhere and moisture from air can permeate through microscopic pores in the rubber brake hoses, nylon master cylinder reservoir, and through various seals from the hydraulic system. As brake fluids absorb water into solution, the local concentration levels are typically low enough to avoid corrosion and when exposed to low temperatures, the solution can also prevent the water from freezing on its own.

A DRAWBACK,

because water increases the solution viscosity at low temperature and decreases the boiling point of the solution. Fluid containing moisture heats up and turns to steam inside the system creating vapor pockets. Brake fluid becomes thus more compressible loosing its ability to transmit the force necessary to effectively stop the car safely.