2008 Chevrolet HHR Owner's Manual - Page 288

Brakes Brake Fluid The brake master cylinder and, on manual transmission vehicles, the clutch hydraulic system use the same reservoir. The reservoir is filled with DOT-3 brake fluid. It is not a good idea to top off the brake fluid. Adding brake fluid will not correct a leak. If fluid is added when the linings are worn, there will be too much fluid when new brake linings are installed. Add or remove brake fluid, as necessary, only when work is done on the brake or clutch hydraulic system. {CAUTION: If your vehicle has too much brake fluid, it can spill on the engine. The fluid will burn if the engine is hot enough. You or others could be burned, and your vehicle could be damaged. Add brake fluid only when work is done on the brake hydraulic system. When the brake fluid falls to a low level, the brake warning light will come on. See Brake System Warning Light on page 3-35. There are only two reasons why the brake fluid level in the reservoir 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 in, the fluid level goes back up. The other reason is that fluid is leaking out of the brake or clutch hydraulic system. If it is, you should have the brake or clutch hydraulic system fixed, since a leak means that sooner or later your brakes or clutch will not work well. 5-34