Air Compressor Oil ?

SPYDERLK · Sep 9, 2015

Compressor oils are different from engine oils in the way they deal with water. I know for sure that they are much better at inhibiting corrosion.

,,, My 1st compressor was a 2 cyl single stage by Campbell Hausfeld. I used engine oil in it for several years with no problem. I retired it when I found a very nice Kellogg American 2 stage. I used the same engine oil in it. It was a tight system - on line 24hr but wouldnt come on for days w/o use of air. I was very pleased. After a few days I found it locked up. Hummed and tripped the breaker when it tried to start. Finally I smacked one of the spokes on the flywheel with a dead blow hammer and it freed up as if nothing had happened. Ran and performed perfect. I turned it off and started monitoring it by turning the flywheel after different idle periods. It was locking up pretty tight after a 24hr period.

I switched to compressor oil and the problem went away ENTIRELY. -- I reasoned that the 2nd stage always sees positive pressure, never suction, and that was leaving the cyl wall almost oil free and water moisture rust locked it at the rings. The added corrosion inhibitors in compressor oil completely prevented it.

I was surprised at so profound a difference.
larry

Soundguy · Sep 10, 2015

I be a syn engine oil may have made 100% difference due to different film / cling properties.

RBLapham · Sep 10, 2015

My compressor, 2 cyl, single stage, 60 gal. no name. Bought in 1990 and used a couple times a month. First oil change - 2014, came out like new. I always checked the sight glass and never got low or dirty. After I moved last year I thought it might be good to change the oil - oil from Home Depot, compressor oil. 25 years and no problems, now maybe I should drain the tank

dodge man · Sep 10, 2015

I changed the oil in my compressor a couple of years ago and used Amsoil compressor oil. I would check the oil and it always looked clean, but I was shocked at how dirty and how much sludge had setteled out of the oil.

SPYDERLK · Sep 10, 2015

I used Rarus 427 in the 10 horse compressor I maintained at work. It stayed clean and full w/o added oil. When I changed it I found a pint of clean clear water under the oil in the sump. ... So it had actually concealed usage of a pint of oil from someone monitoring the sight glass.

Depending on change interval that pure separation could flip to a real problem if it got too full of water.

Bird · Sep 10, 2015

OK, you guys talked me into it. I had a full unopened quart of my compressor oil, and reckon it may have been 4 years since I changed the oil in my compressor . . . . so I just finished doing that. The old oil didn't look bad, and now signs of moisture, but it was slightly darker than the new oil.