The present disclosure is directed to a filter system for a wind turbine, comprising at least a filter device having a filter housing with a volume portion and a cap portion, both defining a filter volume for receiving the oil filter. The filter housing is equipped with an inlet port, an outlet port and a pressure port. The filter system further comprises a pressurizing device having an interface port, and supply means for providing pressurized gas via the interface port, preferably into the filter housing of the filter device. The pressurizing device is configured for being connectable to the pressure port, preferably via a compensation duct. Furthermore, a method is disclosed, wherein the pressurizing device is connected to the filter housing, lubricant is discharged by applying pressurized gas into the filter volume, the cap portion is removed and an oil filter is subsequently replaced.