There is disclosed a method and a hydraulic lubricating apparatus for dosing cylinder lubricating oil. The dosing system includes a supply line and a return line connected with the lubricating apparatus via each one or more valves for supplying hydraulic oil, a central hydraulic oil feed pump connected with hydraulic cylinders, each having a hydraulic piston and which may be subjected to pressure by hydraulic oil via the supply line, a number of injection units corresponding to a multiple of the cylinder number in the engine and which are connected with each their dosing cylinder with a dosing piston and a supply line for cylinder lubricating oil. In order to provide a system which is reliable and cheap and where there is no risk of disruptions, even if a hydraulic cylinder fails, the lubricating apparatus is designed with a distributor plate which at one side is in contact with the dosing pistons and which at its other side is in contact with two or more hydraulic pistons for displacing the distributor plate for activating the dosing pistons.