Auto Systems and Repair: Brake Fluid Replacement

Why Should It Be Serviced?

Old brake fluid may affect brake performance, so it's important to have it serviced. If you don't, you may experience one or more of these symptoms:

  • Brake and/or ABS light may illuminate
  • Soft or spongy brake pedal
  • Internal corrosion of braking system components

When Should It Be Serviced?

  • We recommend brake fluid service every four years or 60,000 miles. Having it serviced at these intervals will help reduce the chance of any related drivability concerns. Your vehicle may have a brake fluid service internal recommend by the manufacturer, please consult your owners manual for vehicle specific information.

How It's Done

First the old fluid is removed from the brake master cylinder and new fluid is added. The brake bleeder screws are then manually opened one at a time, in succession, beginning with the wheel farthest from the master cylinder and finishing with the one closest. This allows fresh fluid to flow through each branch from the master cylinder which is keep full of fresh fluid throughout the process. This not only fills the reservoir and the hydraulic system with fresh brake fluid, but also purges any trapped air, thus "bleeding" the brakes. Specialized equipment can be used for this service or it can be performed manually.

Additional Notes

Prior to the advent of the anti-lock brake system (ABS), replacing the brake fluid was not commonly recommended. In most cases, the brake fluid was only serviced when one of the hydraulic components required replacement. These component failures could often be traced to dirt or debris in the brake fluid, but the affected parts were generally not that expensive to replace.

Modern ABS systems use a sophisticated hydraulic valve assembly that can also be damaged by dirt or debris in the brake fluid. In order to help protect this expensive part, many manufacturers have begun recommending periodic brake fluid replacement. Unless your manufacturer recommends otherwise, replacing the brake fluid every 60,000 miles or four years is good preventive maintenance for any vehicle.