Wheel hub oil seal is a daily car maintenance. The number of times the car oil seal may be replaced belongs to the auto parts with a large amount. Parts such as rolling bearings or sliding bearings are used to prevent lubricating oil or other oil leakage or leakage, etc., and can also prevent dust from infiltrating, maintain good lubrication conditions for rolling or sliding friction parts, and prolong service life. Engine: Crankshaft – front and rear oil seals of the crankshaft, valve – valve oil seal, transmission – front and rear oil seals of the transmission, transfer case – front and rear oil seals of the transfer case, etc. The car parts need oil seals.