bowser vs oiler

bowser

noun
  • A road vehicle (often a trailer) for the transport of liquid fuel, particularly aviation fuel at an airfield. 

  • A buffoon or imbecile. 

  • A fuel metering/delivery pump at a filling station. 

  • A mobile water tank deployed to distribute fresh water in emergency situations where the normal system of piped distribution has broken down or is insufficient. 

oiler

noun
  • An oil tanker. 

  • 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 well. 

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