Abstract: An apparatus (38) is disclosed for controlling the level of oil in one or more compressors (10) of a refrigeration system. The compressors (10) are supplied with oil from a reservoir (28) which is in fluid communication via a common conduit (32) and second conduit (98) with the oil sump (not shown) of each compressor (10). The apparatus (38) includes a housing composed of a main body portion and a spacer block. The body portion is provided with a chamber which houses a float. The chamber is in fluid communication with the oil sump of its respective compressor (10). As the oil level within the compressor (10) varies, the angle of pivot of float also varies. This variation is sensed by a sensor which produces a signal indicative of the level of the oil. When the signal is indicative that the level of oil within the compressor is below a first predetermined minimum level, solenoid valve (78) is opened and solenoid valve (82) closed.