oiler vs serviceman

oiler

noun
  • An assistant in the engine room of a ship, senior only to a wiper, mainly responsible for keeping machinery lubricated. 

  • One who or that which oils. 

  • A small (typically thumb-sized) metal container of oil, often containing an integral brush. 

  • An oilskin coat. 

  • A Mexican. 

  • An oil tanker. 

  • An oil well. 

serviceman

noun
  • A person, especially a man, employed in service and maintenance of equipment. 

  • A man who serves in the armed forces. 

How often have the words oiler and serviceman occurred in a corpus of books? (source: Google Ngram Viewer )