Viton (Fluorocarbon)
Like any element of the engine, oil seals are subject to wear. Over time they can lead to possible leaks of lubricating liquid.
Case study 2: Silicone oil leakage
In addition to preventing oil leakage, the piston oil seal also helps to reduce friction between the piston and the cylinder wall. This is important for maximizing engine efficiency and prolonging the life of the engine components. By reducing friction, the seal helps to improve fuel economy and reduce wear and tear on the engine.
piston oil seal

Obtaining adequate adhesion of fluoroelastomer compounds to metal inserts is a major consideration in fabrication of shaft seals. Adhesive systems worked out for bisphenol-cured VDF/HFP/TFE elastomers often do not perform adequately for peroxide-curable fluoroelastomers and more base-resistant polymers that contain little or no VDF. The trend toward use of more resistant fluoroelastomers in shaft seals has necessitated considerable effort on compounding and adhesive system development to get adequate bonding of the new materials. Silane-type primers are often used to coat metal inserts; these contain residual active groups such as amine functions that interact with the fluoroelastomer compound to attain good adhesion, especially for VDF/HFP/TFE elastomers. Other adhesive systems, using epoxy compounds or tie-coats, may be necessary for difficult bonding situations.3