Substandard or Contaminated Brake Fluid
WARNING: This page is about a different car, the 2010 Suzuki Kizashi. However, it is still accessible from the selected car via links, so may be relevant.
Substandard or contaminated brake fluid with mineral oil or moisture will lower fade resistance or deteriorate rubber parts resulting in the leakage of brake fluid.
In case improper brake fluid as mentioned above entered into the brake system, or in case such doubt exists, disassemble the system and clean the parts with alcohol. For the parts which cannot be disassembled, replace them as an assembly. Rubber parts and brake hoses should be replaced with new ones.