captain wrote:The advantage of synthetic oils over others is the resistance to heat and the higher flash point. I have never heard of any oil specifically needed for normal oxygen concentrations. By normal I mean 20% to 36%, which is plain air to common nitrox percentages. Higher percentages and pure oxygen require an oilless compressor such as the Rix. Any synthetic oil that meets the viscosity requirement of the compressor should work. There is an old saying among mechanics, any oil is better than no oil.
I agree with all but the "old saying.... any oil is better than no oil"...but I am sure that Captain is actually more particular than that with his compressor. Some oils may have too low a flash point for breathing air use and could be more likely to end up with combustion products in the breathing air in an overheating event.
We sometimes (rarely, but with good results) use Mobil One synthetic motor oil in order to meet some lighter viscosity requirements, and their multi-grade properties are helpful. The only synthetic compressor oils we stock are equivalent to 30 and 40 weight, and aren't multi-grade rated. I have used Mobil One (I think it was 20W50) in one of my compressors during the winter when the oil pump would not pick up cold 30 weight soon enough to suit me.
Jim Sheldon will know what works best in the Cornelius.