GMC 2003 Safari Owner's Manual page 260

Checking Brake Fluid
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. See Part C: Periodic
Maintenance Inspections on page 6-30.
You can check the brake fluid without taking off the cap.
Just look at the brake fluid reservoir. The fluid level
should be above MIN. If it isn't, have your brake system
checked to see if there is a leak.
After work is done
on
the brake hydraulic system,
make sure the level is above the MIN but not over the
MAX mark.
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