Since early recorded history, humans have been harnessing the energy of wind through various devices, such as wind turbines. Wind energy has been developing very rapidly in the past years. Wind turbines are one of the machines that utilize wind energy to generate electric power. The installation of wind turbines has undergone a significant growth rate of double-digits in the last decade. Wind turbines consist of various components, such as nacelles, brakes, rotors, yaw systems, drive systems, and wind turbine gearboxes. The wind turbine gearbox is the most crucial component in terms of high rates of failure and downtime. Thus, wind turbine gear oil is indispensably used to maintain the proper functioning of a wind turbine gearbox. Wind turbine gear oil should possess necessary characteristics such as viscosity, pour point, foaming characteristics, steel/copper corrosion, and scuffing load resistance.