Hello everyone,

My name is Hugo and I am a mechanical engineering student from Brazil. I am working on a heat pump that uses CO2 (R744) as its refrigerant. The heat pump uses an Embraco EK6210CD compressor, made for CO2 usage.
Long story short, the piston broke, Embraco wouldn't sell us another compressor, we had to open it up and machine a new piston. The new one works fine. The thing is, now we need to find out which lubricant oil to use, since we no longer have the original one. I can't find it anywhere. Can anyone shed a light on this issue for me?

I thank you guys in advance.