Brake fluid is one of the most overlooked fluid during car servicing routine. This has been so because people are not aware of the characteristics of the brake fluid.

Brake fluid is hygroscopic in nature. This means it readily absorb moisture from the air into your brake system through brake hoses, rubber seals and brake master cylinder reservoir. Eventually, when the moisture content is too high, the boiling point of the brake fluid will drop to such crucial level that it may start boiling during hard braking. This is very dangerous as brakes can fail completely. Besides, the corrosion inhibitors in the brake fluid will degrade over time.

Because of this, many vehicle manufacturers specify in their service manuals that brake fluid should be flushed or changed every two years, and most workshop professionals would agree that it should be periodically checked as well.

Brake fluid is not considered a “top-up” fluid. When the brake fluid level is low, there is usually a problem. Typically, brake fluid level drops when the linings of pads or shoes wears off and the brake calipers or wheel cylinders have to extend further to compensate for it. When used to “top-up”, the added brake fluid may have to be removed when changing new pads or shoes as an overspill might occur when the pistons are pushed back to its intended position. More crucially, the drop in brake fluid can be caused by a leak in the braking system. This can be critical as the loss in hydraulic pressure can cause a significant loss in braking ability. If the brake fluid level continues to drop despite “top-ups”, do pay a visit to the mechanic.