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

Where loads are light, the outer skin layer can be made of silicone. It can be made of Fluroelastomer (orViton) to protect under high temperatures (more than 120 degrees Celcius). The skin can also be made of Poly Acrylate or Polytetra-FluroEthylene.
Oil seals are used in a great many devices for steel production equipment.
Figure 7 shows the places where each seal type is used in a rolling mill.

Dust lip
Material Code ISO 1629
Modern engine oils, such as the current SG classification for gasoline engines, contain a large fraction of additives, many of which are detrimental to fluoroelastomers. The primary functions of oil-additive packages are to protect metal parts, avoid deposits in the engine, minimize oil degradation, and adjust fluid viscosity. Little attention has been paid to avoiding damage to rubber seals. Instead, elastomer producers have been expected to provide new, higher-performing products at no increased cost to auto manufacturers. Among the additives with moieties that may attack fluoroelastomers at high temperature are detergents (phenolates), dispersants (succinimides, alkylphenol amines), and antioxidants (amines, sulfides, hindered phenols).4 Many of these components are multifunctional, containing phenol or amine groups that can dehydrofluorinate and crosslink VDF-containing fluoroelastomers, leading to loss of elongation and eventual embrittlement. However, the rate and extent of reactions with seals are affected by many factors, including whether air is present in the system. When oil is exposed to air at high temperature, additives may undergo considerable changes. For example, a significant fraction of amines may be oxidized to amides, which have little effect on fluoroelastomers.5