Dont know where to put oil in Craftsman 1/2 " Impact wrench

I just bought one of these also. Manual says oil goes into "the air inlet" which I'm thinking is where you attach the hose. That way the oil is sprayed throughout the interior of the gun once you run air through it.
Question for you: I can't get an impact socket onto this gun, almost seems like the square hole is too small. (yes, both are 1/2" drive). How do you get a socket on this stupid thing?
(man that sounds like I'm an idiot, but I've spent a half hour leaning all my body wight, wiggling, etc. and can't get a damn socket on)

Squirt in ( marvel mystery oil) thin oil, preferably air tools oil where the hose hooks up below the handle. Pull the trigger a couple of times(your hand will get alittle wet from the exhaust) before using on job. Good luck,best regards.