A merchant mariner credential grants entry to the starting level of the deck, engine and stewards department. The entry-level rating of oiler is the starting rating for the engine department. An Oiler, also called wiper, is responsible for the maintenance and general cleanliness of the engine department. Their role consists of cleaning the engine spaces and machinery. This might include changing oil, lubricating parts, inspecting gauges and taking out the trash. When not assigned a specific task, a wiper would assist the engineers as directed.