Simply stated, oil seals are components of a machine that seal lubricants. Lubricants are used in the friction-producing areas of a machine to ensure smooth movement and long life, and oil seals, pin seals are used to prevent this lubricant from leaking through bearing clearances of the machine. moq: 1000pcspackae: polybag and cartonsample lead time: 7 daysoemodm: welcome.