Ford 2009 F-250 Owner's Manual page 396

Maintenance and Specifications
7. If the fluid is low, add fluid in small amounts, continuously checking
the level until it is between the MIN and MAX range. Refer to
Maintenance Products Specifications and Capacities in this chapter
for the proper fluid type. Be sure to put the cap back on the reservoir.
BRAKE FLUID
• Vacuum boost system
• Hydroboost system
The fluid level will drop slowly as the brakes wear, and will rise when the
brake components are replaced. Fluid levels between the "MIN" and
"MAX" lines are within the normal operating range; there is no need to
add fluid. If the fluid levels are outside of the normal operating range the
performance of your brake system could be compromised; seek service
from your authorized dealer immediately.
396
2009 F-250/350/450/550 (f23)
Owners Guide, 2nd Printing
USA (fus)