The demand for lower vibration and longer service life has propelled the evolution of magnetic recording hard disk drive motors from ball bearings to uid bearings [1-3]. Fluid bearings incorporate a self-pressurized oil lm, <10 μm thick, between the rotor and the stator. Internal pressure is provided by a groove pattern on the shaft. The thermophysical properties of uid bearing oils and formulation with antioxidant and corrosion inhibitor are described in Ref. [4]. This chapter focuses on materials for charge control and surfactants to reduce the oil evaporation rate.