This precious substance has equal chances for being of any of the four basic sorts - air, earth, fire, or water. (Roll d4 to determine which sort is discovered.) This oil gives total invulnerability to normal elemental forces on the Prime Material Plane: normal wind storms, fires, earth slides, floods, and so forth.

Additionally, there is a 10% chance that any container of this oil which is discovered will be usable on any of the Elemental or Paraelemental Planes. The oil allows the person(s) treated to operate freely and without danger of harm by elemental forces. 

Of course, monsters do other sorts of damage, and such attacks by elemental creatures will still be effective, but at -1 per die of damage. 

The oil comes in sufficient quantity to coat one individual for eight days duration, or eight individuals for one day.