Oil moves in a slimy manner. It moves more slowly compared to Water and does not bounce as effectively. Oil is required to complete Wolfie's levels and fueling Lanterns. If it reaches Weslie's pipe point, the level is failed. Oil will also destroy Bells in contact.
Reactions with Fluids
If mixed with Water, the Oil rises above the Water, due to its lighter density.
If mixed with Hot Oil, the Oil will be burnt into more Hot Oil.
If mixed with Toxic Water, the latter turns into more Oil.
Notable Reactions with Objects
Vines are petrified like Ooze from Where's My Water?.
Oil will be burnt into Hot Oil if it comes in contact through the flames of a Fire Switch.