The notes here are taken from the actual Scala, so be warned that references to the "previous" proverb refer to its order in the Scala, not its order here. You can read more about the word at the Verbosum blog: OLEUM.
Oleum in ignem.
Oleum camino addis. ~ Note: This is one of the sayings that Erasmus included in his Adagia, 1.2.9.
Ingrato benefaciens perdit oleum et operam.