I have a 10 ton Copeland discus and a 15 ton copelamatic on a rack system. This is a R22 system. They share a common hot gas line and suction line. The discus maintains a constant oil pressure out put at the pump of 90 pounds. The copelamatic on start up has a oil pressure output of about 85 pounds but it slowly falls and eventually trips my oil pressure control. The discus is a new compressor. The previous discus was doing the same thing. It busted one of the connector rods. The oil pump is new, I have a crank case heater on the comp and there is no foaming in the sight glass. The oil level is 1/2 way up the sight glass. I have installed a new oil separator on the system and it works great. This system is at a Save A Lot store and takes care of medium temp display boxes. It seems like there is an internal oil leak in the compressor causing the oil pressure to fall off. Has anyone encountered this problem before?