oiler vs trooper

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. 

trooper

noun
  • A cavalry horse; a charger. 

  • One who endures adversity or hardship with an attitude of stoicism and persistence. 

  • A mounted policeman. 

  • A soldier. 

  • A soldier of private rank in cavalry or armour. 

  • A troopship. 

verb
  • To work steadily at an unpleasant job without complaint. 

  • To work as a trooper. 

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