Abstract: Provided is a lubrication system for a drive train of a wind turbine including a main oil tank including a lubrication liquid, for lubricating the drive train when the wind turbine has connection to a grid and a main reservoir which is separate from the main oil tank and contains lubrication liquid for the drive train when the wind turbine has no connection to the grid. The main reservoir includes a first reservoir containing a first amount of lubrication liquid for at least a first component of the drive train and a second reservoir including a second amount of lubrication liquid for at least a second component of the drive train. The lubrication system is configured to supply the oil from the main reservoir to the drive train when the wind turbine has no grid connection for creating an oil sump in at least the second component of the drive train.