Did a lot of note-taking, and even a survey here at one point. Did not find any commonality with hours, oil being run, or even favorite RPM's they're run at.

ONLY common factor I could identify was "sitting". A moderately higher number would fail after the engine had been parked for 3 or more weeks, then run. That's what sparked the idle of lubricating the compressor if it will be stored for any length of time.

Lots and lots of internet "hype" out there on compressors... especially stuff that claims "old ones were bad" or "new ones are good". Seldom do you see me go this far... but most of that talk is simply "BS".

You see, sometimes a manufacturer has to change a design just so they can apply for a new patent (such as might happen if the vendor who made them went out of business, for instance).