Shimano Hydraulic Disc Brake Fluid - 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

One of the only bits of maintenance an internally geared hub needs is occasional oiling. Using the proper oil is essential, and, if you have a Shimano Alfine hub, you've found the right stuff. - Mineral oil based lubricant specifically for the Alfine 11-speed hub