Shimano Hydraulic Mineral Oil

Always repair/flush SHIMANO disc brake systems with SHIMANO genuine mineral oil. Dirty brake fluid decreases the brake's performance and can damage seals, leading to leaks and even failure over time.
This is why it is very important to have your brakes bled and the fluid flushed regularly.

Non-corrosive mineral oil that offers excellent heat expansion properties
Mineral oil will not absorb water from the air
Not caustic and is non-toxic