Chevrolet Volt 2012 Owner's Manual page 306

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 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.
When the brake fluid falls to a low
level, the brake warning light comes
on. See
.
Check brake fluid by looking at the
brake fluid reservoir. See
.
With the vehicle not running for at
least one minute, the maximum fluid
level (A) is at the top of the reservoir
body. With the vehicle running, the
fluid level should be in the proper
operating range (B) between the
MIN and MAX marks. If it is not,
have the brake hydraulic system
checked to see if there is a leak.
After work is done on the brake
hydraulic system, make sure the
level, with the vehicle running, is in
the proper operating range (B)
between the MIN and MAX marks.
Use only new DOT 3 brake fluid
from a sealed container. See
Always clean the brake fluid
reservoir cap and the area around
the cap before removing it. This
helps keep dirt from entering the
reservoir.
.