1997 GMC Sonoma Owner's Manual - Page 270

Checking Brake Fluid What to Add When you do need brake fluid, use only DOT-3 brake fluid -- such as Delco Supreme 11 (GM Part No. 12377967). Use new brake fluid from a sealed container only. @ Always clean the brake fluid reservoir cap and the area around the cap before removing it. This will help keep dirt from entering reservoir. the ~ You can check the brake fluid without taking off the cap. Just look at the windows on the brake fluid reservoir. The fluid levels should be above MIN. If they aren't, have your brake system checked to see if there is aleak. After work is done on the brake hydraulic system, make surethe levels areabove MIN and below the top of each window. With the wrong kind fluid i your brake of n system, your brakes may not work well, or they may not even work all. This could cause a at crash. Always use the proper brake fluid. 6-32