Took a look at a split heat pump, where the compressor was located 20 feet higher than the air handler. No p-trap on the air handler and unit has a history of compressor change-outs. 4 already, current compressor is nosiy like hell and vibrating. So all the symptons of oil logging. I installed an oil separator on the unit, and a p trap on the suction line, unit is working fine now. However, I'm still concerned about the amount of oil still in the system. This unit currently has 150 feet of piping in a commercial occuped environment, too late to make piping changes other than the p-trap. Is there a way of getting out all the oil in the system and how please?