Dynamic seals are used in situations that involve motion and are classified by the movement of the objects they are placed in. The types of motion include rotating, oscillating, and reciprocating motion. The performance of dynamic seals is usually influenced by interrelated environmental factors, such as: lubrication, thermal cycling, friction, and more. In order to create the best dynamic seals, all of these factors must be considered. For dynamic seals, the material used must be suitable to the heat exposure the device will endure. While these gaskets keep contaminants from entering the engine, they also may have to withstand a great deal of pressure. Rope packing and synthetic rubber are usually the choice materials for automotive dynamic seals.