So shifting this thread back from a potential hole of electrical discussion ...
This compressor that I'm looking at seems to be of an early 2000's vintage, and has mostly likely been running mineral oil all its life. Based on prior threads (albeit some 10+ years old) mineral oil is frowned upon for continuous mixing nitrox, and I haven't come across anything conclusive about changing from mineral to synthetic. Is it sufficient changing to synthetic, continuing to change oil on shorter cycles until most of the carbon deposits are flushed out, or does it require a pull-down and thorough clean?