the.com/oiler

means A person, tool, or device that applies oil to machinery parts to keep them running smoothly and quietly.

from Simple agent-noun construction: 'oil' (from Old French 'oile,' tracing back to Latin 'oleum,' meaning olive oil — the original lubricant of the ancient world) plus the '-er' suffix marking 'one who does.' The word rode in on the Industrial Revolution, when factories full of grinding gears needed someone, or something, whose entire job was squirting oil into the right joints before they seized up. It later picked up extra lives as slang — oilskin raincoats, oil tankers, and even oil-rich Texans have all been called 'oilers' at one point or another — but the core sense has always stayed close to its greasy, practical roots.