Bone oil seals are a typical representative of oil seals, and what is generally referred to as an oil seal is actually a bone oil seal. The primary function of an oil seal is to isolate the lubricated components within the transmission parts from the external environment, preventing the leakage of lubricating oil. The bone serves as reinforcement, similar to rebar in concrete structures, to maintain the shape and tension of the oil seal. They can be categorized into single-lip and double-lip bone oil seals, with the secondary lip of the double-lip seal providing dust prevention, keeping out external dust and impurities. According to the structure, they can be internal, external, or assembled. Depending on working conditions, they are classified as rotating or reciprocating bone oil seals. They are used in crankshafts of gasoline and diesel engines, gearboxes, differentials, shock absorbers, engines, and vehicle axles, among other components.