Related Terms • Brakes • Brake Bleeding • Brake Drum • Brake Fluid • Brake Job • Brake Lining • Brake Pad • Brake Rotors • Brake Shoe • Caliper • Hygroscopic • Parking Brake • Master Cylinder • Wheel Cylinder

Definition: The brake system uses a glycol-based hydraulic fluid. The fluid is "hygroscopic," which means it tends to absorb moisture over time (never leave a can of brake fluid open for this reason). Moisture lowers the boiling point of the fluid and causes internal corrosion in the brake system. That’s why the fluid should be replaced when brake repairs are made or every two years for preventive maintenance. There are several different types, based on the boiling temperature and other characteristics of the fluid. DOT 3 or DOT 4 is used in most passenger cars and light trucks. Use only the type of fluid specified by the vehicle manufacturer. Using DOT 3 in an application that calls for DOT 4 might create a safety hazard. DOT 5 brake fluid is different from DOT 3 and DOT 4 in that it is silicone-based. DOT 5 is NOT recommended for any vehicle equipped with antilock brakes - but it can provide long-lasting protection against corrosion for vehicles that are stored for long periods of time or are driven in wet environments.

Related Resources:

DIY: Disc Brakes
These instructions will help you change the disc pads on most popular vehicles. Be sure to READ these instructions completely before you begin.

DIY: Drum Brakes
This is a good job for a moderately skilled DIY. It only takes about three hours to do and will save you quite a few bucks. Plus you will get the satisfaction of saying "I did it myself!"

DIY: Wheel Cylinders
Here's a good job for the DIY that's easy and will save you a few bucks.

Bargain Brake Jobs
Your brakes are the most important part of your vehicle. You need to be sure the job is done completely and correctly.