When used, snake oil temporarily renders enemies unable to shoot as they will be attempting to get liquid off themselves. After they begin to move again, their movements will be slowed down for a brief period.
Professor Perry uses Snake Oil as a weapon during his fight against Jack Swift, taking a swig from the bottle and then spit it back out at the player. Perry will heal himself several times over the course of the fight by drinking Snake Oil. Spitting Snake Oil is also his special move in Showdown Mode. NPCs refer to Perry as a "charlatan snake oil salesman."
It can first be obtained during the mission "The Mine" by interacting with a corpse that is inside the cell where the mission begins. It costs $400 for a quantity of five and only five can be purchased at a time.
Snake Oil was originally used by Chinese railroad workers as a remedy to treat joint pain while working; it was made from Chinese Water Snake. The ointment was introduced to other European workers with joint pains who would later exaggerate its effectiveness.
Snake Oil is only available in certain stores in the game.
Nigel West Dickens is a stereotypical snake oil merchant who appears in many story missions. The player cannot actually buy snake oil from Mr. Dickens, however.