O-rings are made of a number of substances including polyurethane, silicone, neoprene, nitrile rubber or fluorocarbon. The purpose or function of an O-ring is to provide a tight seal between two objects. You can find O-rings in a variety of products like water hoses, hydraulic cylinders, faucets and hummingbird feeders. It is important to apply vegetable oil to O-rings to keep them lubricated to maintain a tight seal and to keep them from drying out or rotting.
Remove the O-ring. Some O-rings can be lifted out with your fingers while others need to be gently pried with a screwdriver.
Pour a small amount of vegetable oil in your palm or a small lid.
Stick your finger in the oil and then apply the vegetable oil on the O-ring.
Rub all areas of the O-ring with oil. Reapply once a month or as needed to keep the O-ring flexible.