Oil separator for an internal combustion engine

An oil separator for separating oil from gases emanating from a crankcase (1), has oil-collecting means (11) associated with a siphon (12) having its inlet in the interior of the oil separator (7) from an oil recovery chamber (13) is surrounded, whose wall is pierced: - by at least a small oil recovery hole (14) which is provided at the lowest point of the chamber (13) at the outlet of the collecting means (11); - by at least a small vacuum-hole (15), which is at the highest point of the chamber (13) provided above the surface of the decanted oil, and the chamber (13) with a vacuum point (16). The oil separator according to the invention is used in an internal combustion engine.