Oil-cooled screw compressor system and method for modifying same

An oil-cooled screw compressor system is provided with: a first lubricating oil supply route which supplies lubricating oil to a screw section; and a second lubricating oil supply route which supplies lubricating oil to a bearing. The first lubricating oil supply route is provided with: a gas-liquid separator into which discharge gas from a screw compressor is introduced and which separates lubricating oil from the discharge gas; a first supply flow passage which is formed in a housing wall, is open to the outer surface of the housing wall, and is in communication with a screw chamber; and a first supply passage which is connected to the lubricating oil storage region of the gas-liquid separator and to the opening of the first supply flow passage. The second lubricating oil supply route is provided with: a lubricating oil storage tank; a second supply flow passage which is formed in the housing wall, is open to the outer surface of the housing wall, and is in communication with a bearing chamber; a second sup