You need the oiler or you will eventually kill the compressor. The Freon used to do the lubrication. I keep my oiler turned up for max oil. I would rather have oil in my air lines than water when it freezes. I believe some guys have told me the York doesn't need the oiler though. I would still run a good air filter on its intake so you aren't sucking up a ton of dust.

Traded that truck in for a new full size Bronco in 1979 (gas was $.42/gal then) the compressor still worked then. Totaled the Bronco with 6000 miles on it, that truck has probably gone back and forth to Japan 5 times as Toyotas by know. And yes that does make me feel old.