The advantage is that the coefficient of internal friction is small, so the energy consumption to overcome the friction is less, the flow of thin oil is good, it is easy to enter the friction surface of each lubrication point, it has a good cooling effect, and it can take away the impurities adhering to the friction surface and the metal particles caused by grinding. The disadvantage is that the oil film can not withstand large unit pressure, and the requirements for sealing are high. High speed presses generally use large flow thin oil lubrication, which can take away the heat generated by each friction pair.