Oil charge for a Grasso ms1027c mono screw comressor

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.

Attachment 15287
This is the original oil table, 1984!.
All are basic mineral oils and NH68 did not exist at this time.
I'm not found of your artic SHC NH68!
bad experiences on old systems.