Is normal hydraulic brake fluid low viscosity mineral oil?

No, normal hydraulic brake fluid is not low viscosity mineral oil. It is typically made from either glycol-based or ester-based compounds, which are formulated to withstand high temperatures and pressures. These fluids are designed to provide effective braking performance and prevent corrosion in the braking system. Mineral oil can be used in some specific applications, like certain bicycle brakes, but it is not the standard for automotive hydraulic brake systems.