Chevrolet 2003 Impala Owner's Manual page 298

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.
When your brake fluid falls to a low level, your brake
warning light will come on. See Brake System Warning
Light on page 3-33.
What to Add
When you do need brake fluid, use only DOT-3 brake
fluid. Use new brake fluid from a sealed container
only. See Part D: Recommended Fluids and Lubricants
on page 6- 16.
Always clean the brake fluid reservoir cap and the area
around the cap before removing it. This will help
keep dirt from enterina the reservoir.
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.
\.
.-..
-he wrong kind c . .hid in y--r b . , . c e
system, your brakes may not work well, or
they may not even work at all. This could
cause a crash. Always use the proper brake
iiuid.
I
5-45