In previous eras there were oiler positions in various industries, including maritime work (naval and commercial), railroading, steelmaking, and mining.
Today most such positions have been eliminated through technological change; lubrication tends to require less human intervention, so that workers seldom have oiling as a principal duty.
In the United States, Title 46 (Shipping) of the Code of Federal Regulations governs who is eligible to sail as an oiler in National trade.
In order to obtain this certificate the applicant must first have no less than six months of documented sea time working under the supervision of a watch keeping engineer.
It is also required for all sea going personnel to have MED (marine emergency duty) certificates which can be obtained by taking courses through a college approved for training.