Is all gear oil hypoid oil?

Not all gear oil is hypoid oil. Hypoid oil specifically refers to lubricants designed for hypoid gears, which have a unique tooth design that allows for smoother operation and higher torque transfer. While hypoid oils typically have additives to handle the specific demands of hypoid gear sets, there are other types of gear oils formulated for different gear types, such as bevel or spur gears, which may not require the same properties. Therefore, while all hypoid oils are gear oils, not all gear oils are hypoid oils.