If you read your owner's manual, you should see that the brake fluid must be changed after 2-3 years, in ANY car. When the fluid turns dark, it gets more acidic, and can destroy the seals in caliper pistons, brake wheel cylinders, and master cylinders. It can cause pistons to seize up. You should have your brake system bled out, and the fluid changed. You should not mix the fluid from other manufacturers. Get genuine Ford brake fluid to do this job. If you are ambitious, you can exercise your pistons back into shape after the change. Remove your front wheels, and gently pry on the piston until it recedes. Pump it back up with the pedal. Do this 4-5 times to dislodge any sludge that may have accumulated around the piston seals. This should improve your brake performance all around. Good Luck!
