Changing compressor oil ?

[Ilikeike]

Annually, at home and work, with Mobil Rarus 427.
I just did them last week.

Also changed the compressor valve plate on my home Dayton 60gal for the first time 20 yrs. it's noticeably quieter now,I'm sure the little reed style valves weren't closing completely after all that time.

 

[viikinki]

Once in a year. Oil is Teboil diamond 5w-40 diesel engine oil.

 

[redmondjp]

How come the guy that didnt change for 40 yrs doesnt need a new unit then?

It all comes down to how many hours the compressor gets used, along with atmospheric conditions (dew point/humidity level) and condition of the pump rings (how much blowby).

On my new-in-1990 60-gallon Ingersoll Rand compressor, I have changed the oil once, somewhere around 1998 or so. Oil level is still fine, looks the same, and there is no moisture in the crankcase. It still works fine.