A film of oil coats the character, increasing vulnerability to fire. Remove with a Handkerchief.
The status is inflicted by the spell of the same name and certain enemies and traps can also inflict the status, such as Firaja, the boss Belias's special move. The Gillie Boots accessory makes their wearer immune to Oil.
In the original PSX version, Oil status has no effect due to a glitch, despite its description in the game manual or in-game help message. In the PSP remake, it functions as intended as a status effect that doubles the effect of fire attacks on the afflicted character. The afflicted character will turn a certain gray and a oil drop icon floats above it. It is normally caused by a Bomb's Self-Destruct or a Ghost's Oily Touch, but other enemy attacks such as Malboro's Bad Breath or Reaver's Bio can cause it. It can be removed when the character is attacked by fire, or using Remedy.
Per usual, it increases the amount of damage a unit take from fire element attacks. A Green Mage can learn the Oil spell, and a Blue Mage can learn Unction from a Red Marshmallow, both of which inflict the Oil status. A Spellblade can learn Oil Blade from the Broadsword. Oil is cured by the Handkerchief or Remedy items.