Why do not add oil to electric winch when it leaves the factory

Why do not add oil to the electric winch when it leaves the factory：In order to facilitate loading, unloading and transportation, the winch is generally not filled with lubricating oil before use. N150 extreme pressure industrial gear oil is recommended at room temperature.Lubricating oil replacement cycle: the first change of lubricating oil shall be carried out after the first 200 hours of operation of winch reducer, and the residual oil shall be removed during replacement. After the first oil change, the lubricating oil should be changed every 3 months for the winch reducer which works continuously for more than 10 hours every day, and the lubricating oil should be changed every 6 months for the winch reducer which works for no more than 10 hours a day. The gearbox of winch which has not been used for a long time (generally more than 12 months) must be replaced with lubricating oil before reuse. Different types of lubricating oil can not be mixed!