What about Neoprene O-Rings?

Neoprene is a commercial name for polymers comprised of chloroprene.  It is the first commercially successful substitute for natural rubber in the United States.  Neoprene combines good resistance to weathering and petroleum-based lubricants, a wide temperature range and exceptional economy.

Neoprene is commonly used as a material for fly fishing waders, as it provides excellent insulation against cold.  Recently, neoprene has become a favorite material for lifestyle and other home accessories including laptop sleeves, tablet holders, remote controls, mouse pads, and cycling chamois. In this market, it sometimes competes with LRPu (low-resilience polyurethane), which is a sturdier (more impact-resistant) but less-used material.

Individual neoprene compounds have service temperatures within the range from minus-65 degrees to +212 degrees F, including certain compounds formulated for lower temperatures.

Neoprene is alkali and acid resistant, flame retardant and suitable for petroleum based oils.  Animal and vegetable fats and greases also provide a highly stable environment for this polymer.  Generally speaking, neoprene is noted for good compression set, excellent flex fatigue resistance, and resistance to weather and ozone.  Its excellent adhesion qualities to metals makes neoprene ideal for molding with metal inserts, make it suitable for use in heating, ventilating and air conditioning (HVAC) systems, refrigeration units and numerous dynamic applications.

Neoprene is not effective in aromatic and oxygenated solvent environments.  Neoprene degrades in the presence of some fairly common chemicals, including hydrochloric acid, acetone, xylene, acetic acid, aqua regia, boric acid, liquid butane, hydrogen peroxide, iodine, kerosine, lacquer, lard, motor oil, nitric acid, palm oil, tallow, turpentine, urine, and most chlorine-based chemicals including household bleach.