oil well vs oiler

oil well

noun
  • A hole drilled into the earth from which petroleum is pumped. 

oiler

noun
  • An oil well. 

  • 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. 

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