Most generators have been rebuilt numerous times, and have probably gotten sealed bearings with permanent lubrication in the process. The original oil cups got a drop or two of 30 weight motor oil at every oil change. Chances are the oil cups on your generator are just there for decoration these days, but a tiny drop of motor oil a couple of times a year can't hurt.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!