GM Service Manual Online
For 1990-2009 cars only

Caution: Brake fluid may be irritating to the skin or eyes. In case of contact, take the following actions:

   • Eye contact--rinse eyes thoroughly with water.
   • Skin contact--wash skin with soap and water.

Notice: Brake fluid will damage electrical connections and painted surfaces. Use shop cloths, suitable containers, and fender covers to prevent brake fluid from contacting these areas. Always re-seal and wipe off brake fluid containers to prevent spills.

Use Delco Supreme 11® Brake Fluid GM P/N 12377967, or an equivalent DOT-3 motor vehicle brake fluid. Always store brake fluid in a closed, sealed container. Never use previously opened containers of stored brake fluid. Always use new brake fluid from a sealed container. Brake fluid left in open or improperly sealed containers will absorb moisture. Moisture can lower the brake fluid boiling point, causing the following problems:

    • Brake system contamination
    • Corrosion
    • Deterioration of rubber components

Substandard Or Contaminated Brake Fluid

Notice: Power steering fluid and brake fluid cannot be mixed. If brake seals contact power steering fluid or steering seals contact brake fluid, seal damage will result.

Use the correct fluids on models with a hydraulic booster. The master cylinder and brake system use brake fluid. The hydraulic booster system uses power steering fluid.

If the brake fluid contains improper fluid, water, or other contaminates, the brake fluid may boil or may deteriorate rubber components in the hydraulic brake system.

Evidence of rubber deterioration occurs in the following areas:

    • Swollen master cylinder piston seals
    • Swelling of the wheel cylinder boots
    • Swelling of caliper boots
    • Swelling of the master cylinder reservoir diaphragm

If rubber deterioration is found, replace all rubber parts, including the hoses, in the brake system. Check for brake fluid on the brake linings. Replace the brake linings that are contaminated with brake fluid.

If the brake fluid is contaminated and the master cylinder piston seals are good, check for leaks and excessive heat conditions. If no leaks or excessive heat conditions are found, flush the brake system.

Flushing The Hydraulic Brake System

Flushing the brake hydraulic system is running new brake fluid through the brake system until the brake fluid at each bleeder valve comes out clear.

Flush the brake hydraulic system for the following reasons:

    • When new hydraulic brake parts are installed.
    • When contamination may be present. Flushing is the only way to clean contaminated fluid out of the system.
    • When you do not know the grade of brake fluid in the brake system.
    • When mineral oil is present in the brake fluid.