learning to maintain chillers and also taking a class at the the 597 training school. my question is I had an oil analysis come back suggesting an oil change on yt chiller, oil was dark and analysis showed slight traces of acid. their suggestion was to change oil. not having done this before, our shop has a hyperwatt machine to raise pressure. from my understanding im supposed to connect water hoses to drain and vent ports on evap head one on each end of evap barrel, after hyperwatt is powered up, calibrate to atomphere pressure and connect 1/4 refrig line to any port coming off of evap barrel.set hyperwatt to say 5 psig and start hyperwatt machine pump and heater. run until pressures become positive on evap barrel. at this point can I now drain oil from sump into a bucket until it stops draining? then proceed to manualy pump in new c oil, in the amount I drained? then close off drain valve and power off hyperwatt machine. this is my understanding of what needs to happen. any further feedback whould be helpful. thankyou cannedheat