GMC 2003 Sierra - Manual (Page 422)

Brakes
Brake Fluid
Yaur brake n^asief cylinrlei ressrynir ¡я fiilled with DOT-3
brake fluid. See
Engine Conpäriment Oven/iew on
page 5-12 for the locatton of the reservoir.
Tliene arg only two reabons why the brake Iluid level in
[be ieservolr might go down. The first Is that the
brake fluid goes down lo an acceptable level' during
normal brake lining wear. When new linings are pul in.
the fluid ievel goes back up. The other reason is
lhat fluid ts leaking out of the bnake system. If if
is, you
should have your brake system lixed, since a i&ah
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 oH" your brake fluid.
Adding brake fluid won't correct a leak. If you add fluid
when your linings are worn, then you'll have too
much iluJd when you gel new brake linings. You should
actd (nr remove) brake fluid, as necessary, only when
wor1( is done on Ihp brake hydraulic system.
If you have 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. See "Checking Brake Fluid"
in this section.
Refer to the Maintenance Schedule to determine when
to check your brake fluid. Sea Part
C* Pefíodic
M aintenance (nspections on page 6-16.
5^7