Lump,
Perhaps he means something for the thread on the asa as the lower end guns don't have purges?
if thats that case its alright, the air pressure from the tank is being forced away from both the gun and the thank, meaning that no oil will go into the gun or into the tank.
No you do not put oil any where near compressed air. its as simple as that. there is not one Marker manufacture that will say that. follow the instruction for your marker
Hmm this is sorta confusing :S , i know its not in any way shape or from or sane to put it on your fill nipple unless you wish to die because when you attach it to a compressor the pressure makes it combust ? but the pressure at the ASA is round about 850psi , is that enough to do the same thing ? :s
If its just on the threads of the ASA, i would recommend Dow 33.
If you want the oil to cycle through your marker, leave barrel/hopper OFF the marker, then disconnect the macroline from front inline reg, put a couple drops in front inline reg , reconnect macroline, dry fire marker 50-100 times, wipe off excess oil in breech area and bolt.
Otherwise look or download your markers manual, learn how to strip and perform regular maintainence.