Hy guys, I am servicing an old Grasso mono screw compressor type ms1027c. It runs on a pump system R717. It needs an oil change but no one knows what type of oil the previous service company used so, it needs to be a complete oil change to minimise oil mixing with the following problems.

Any suggestions on what oil to use?

I am betting for Mobil Gargoil Arctic shc nh68.