The Oiling Trough allows you to soak Planed Boards in Oil to Convert them into Oiled Boards.
10L Oil = 25% fill. Each board uses 5% Oil (2L), regardless of the result of soaking.
The Oiling Trough appears to yield an average of 50% Oiled Boards and 50% Warped Boards. A character's proficiency levels do not appear to have an impact on this rate.