When it comes to braking safety, the quality of the brake fluid is of paramount importance. Because the brake fluid is hygroscopic (property of absorbing humidity from the environment), with the high temperatures that the brake systems withstand, there is a danger of formation of vapor bubbles, and the consequent failure of the brake system.
If the liquid does not have an adequate boiling point, and it goes into a gaseous state, when the brake pedal is actuated, the response is not immediate due to the delay caused by compressing the gases that formed. This is the cause of many unexplained accidents as the vehicle momentarily lacks brakes until the system temperature drops again.
Like other components like water and motor oil, brake fluid has a limited shelf life.