Buick 2003 Rendezvous Owner's Manual page 349

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 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 correct a leak. If you add fluid
when your linings are worn, then you'll have too
much fluid when you get new brake linings. You should
add (or remove) brake fluid, as necessary, only when
work is done on the brake hydraulic system.
I
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.
BRAKE
I I I
United States Canada
When your brake fluid falls to a low level, your brake
warning light will come on. See Brake System Warning
Light on page 3-40.
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