This question came up at Engineering SE but remains unanswered. If we are compressing regular air, not nitrogen, what oil or compound can be used that would not combust with the oxygen in the air. High pressures cause high temperature which would ignite hydrocarbon based oils. What compressor or pump lubricant would be suitable in these conditions?
With Internet search, I found this compound, but it is a grease intead of oil and there is no mention of ability to withstand high pressure.