Abstract: The present invention relates to a mechanical system with one-way clutch, for example a pulley for a motor vehicle alternator, comprising a first element and a second element able to move one relative to the other. These elements delimit an annular housing including a one-way clutch device and at least one rolling bearing positioned beside the one-way clutch device. The mechanical system is characterized in that the one-way clutch device is lubricated by a lubricant of a first type, in that the rolling bearing or bearings are lubricated by at least one lubricant of a second type, and in that the lubricant of the first type and the lubricant of the second type are different from and compatible with one another. The invention also relates to an alternator comprising such a system configured as a pulley, and to a method of manufacturing such a mechanical system.