I've seen compressors withstand abuse from poor maintenance or shoddy installation work last as long as a year before the bearings finally failed from liquid dilution or prolonged short cycling,or ?????. Just another way to look at obienoe's response. Three phase, single phase, what does it matter? What really is important is what type of compressor. Screw, scroll, reciprocating. Large or small, cylinder unloading? Can't help until we have better intel.