On 8/7/15 6:38 PM, Uncle Monster wrote:
On Friday, August 7, 2015 at 2:06:55 PM UTC-5, J Burns wrote:


Non-detergent oil is recommended for compressors, but I've read of a
1964 Sears compressor, still in service in 2011, whose manual
recommended detergent oil.

I see two possibilities: it was a misprint, or engineers knew that the
detergent oil on the market (maybe it was SD) did not absorb water.

You can purchase air compressor oil from WW Grainger. I use it in my compressors because it has a very wide temperature range and has kept my compressors running trouble free for decades. Auto parts stores may carry it too but I always bought it at Grainger. ^_^

http://preview.tinyurl.com/nop5tta

[8~{} Uncle Air Monster

Here's Valvolines, more data.
http://www.valvoline.com.au/explore-our-products/all-products/industrial-lubricants-and-hydraulic-oils/compressor-and-air-tools-oils/valvoline-valcomp-compressor-oil

"Fights deposits" seems to describe a detergent oil.

Demulsibility.... This explains it.

http://www.machinerylubrication.com/Read/28786/oil-demulsibility-importance

Oil draws moisture from the air. I wonder if that's true of all oils.