CARS.COM — Can brake fluid go bad? Indeed it can, and you might not be able to tell if it has just by looking.
Most cars have see-through reservoirs for brake fluid under the hood so that owners can check at a glance to make sure it’s at the proper level. That, however, tells you nothing about the condition of the fluid.
Brake fluid absorbs water over time, particularly in areas with high humidity, when moisture seeps through rubber hoses and seals. Water reduces the boiling point of brake fluid, and in situations that put high demands on your brakes — such as mountain driving, towing or making repeated hard stops — the fluid can become so hot that it impairs stopping ability or causes temporary loss of braking power.