The temperature within the oil seal environment is the main factor that dictates the composition of an oil seal. Generally, there is a range of set temperatures that are optimal for that material. If the operating environment is too cold, the seal may become brittle and, at high temperatures, the seal material may show increased elasticity and become leaky.
What Are Oil Seals?

■Anti-wear agents: Anti-wear agents help protect parts of the engine that are especially susceptible to damage from high temperatures, like cylinder walls, lifters, cams, and piston rings. This additive acts as a protective layer around these components to limit friction in metal-on-metal situations.
Typically used in hydraulic high-stress applications where compounds under high pressure are exposed to wear, the benefits of polyurethane seals include: