Oil Pressure Release Valve

pressure release
Relieving pressure from the ischial turberosities (bones on which we sit) every 15 min. in order to prevent pressure sores.
the removal of overlying rock which releases pressure on underlying strata causing them to expand and crack.
The removal of overlying rock from erosion allows expansion and fractures (sheet joints and exfoliation).

valve
A cylindrical mechanism in a brass instrument that, when depressed or turned, admits air into different sections of tubing and so extends the range of available notes
control consisting of a mechanical device for controlling the flow of a fluid
A device for controlling the passage of fluid through a pipe or duct, esp. an automatic device allowing movement in one direction only
device in a brass wind instrument for varying the length of the air column to alter the pitch of a tone
A membranous fold in a hollow organ or tubular structure, such as a blood vessel or the digestive tract, that maintains the flow of the contents in one direction by closing in response to any pressure from reverse flow
a structure in a hollow organ (like the heart) with a flap to insure one-way flow of fluid through it

oil
Petroleum
a slippery or viscous liquid or liquefiable substance not miscible with water
Any of various thick, viscous, typically flammable liquids that are insoluble in water but soluble in organic solvents and are obtained from animals or plants
cover with oil, as if by rubbing; "oil the wooden surface"
A viscous liquid derived from petroleum, esp. for use as a fuel or lubricant
anoint: administer an oil or ointment to ; often in a religious ceremony of blessing