1995 Chevrolet Blazer Owner's Manual - Page 267

Brakes Brake Master Cylinder Your brake master cylinderis here. It isfilled with DOT-3 brake fluid. There are only two reasons why the brake fluid level in your master cylind might go down. The first is that the brake fluid goes down to an acceptable level during normal brake lining wear. When new linings are put the in, fluid levelgoes back up. The other reason is that fluid is leaking of the out brake system.If it is, you should have your brake system fixed, since a leak means that sooner or later your brakes won't work well, or won't work at all. So, it isn't a good idea to"top off' your brake fluid. Adding brake fluid won't correcta leak. If you add fluid when your linings are worn, then you'll have too much fluid when you get new linings. You should add brake (or remove) brake fluid, as necessary, only when work done on the brake is hydraulic system. Refer to theMaintenance Schedule to determine when to check your brake fluid. See "Periodic Maintenance Inspections" in the Index. 6-27