GMC 2012 Savana Owner's Manual page 278

The braking system on a vehicle is
complex. Its many parts have to be
of top quality and work well together
if the vehicle is to have really good
braking. The vehicle was designed
and tested with top-quality brake
parts. When parts of the braking
system are replaced, be sure to get
new, approved replacement parts.
If this is not done, the brakes might
not work properly. For example,
installing disc brake pads that are
wrong for the vehicle, can change
the balance between the front and
rear brakes for the worse. The
braking performance expected can
change in many other ways if the
wrong replacement brake parts are
installed.
The brake master cylinder reservoir
is filled with DOT 3 brake fluid. See
for the location of the
reservoir.
There are only two reasons why the
brake fluid level in the reservoir
might go down:
The brake fluid level goes down
because of normal brake lining
wear. When new linings are
installed, the fluid level goes
back up.
A fluid leak in the brake
hydraulic system can also cause
a low fluid level. Have the brake
hydraulic system fixed, since a
leak means that sooner or later
the brakes will not work well.
Do not top off the brake fluid.
Adding fluid does 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 hydraulic
system.
If too much brake fluid is added,
it can spill on the engine and/or
fuel operated heater parts,
if equipped. If the vehicle has a
diesel engine and a fuel operated
heater, see Fuel Operated
Heater (FOH) in the diesel
engine supplement. The fluid
will burn if the engine is hot
enough. You or others could be
burned, and the vehicle could be
damaged. Add brake fluid only
when work is done on the brake
hydraulic system. See Checking
Brake Fluid in this section.