ERIKS type M (type B according to the DIN standard) has a single metal casing and rubber sealing lip. Since the casing is made of metal, it must be fitted in a well-finished, undamaged groove. Large volumes of oil seals with metal casings are often cheaper, which is why they are often used as original equipment in machines. However, if an oil seal has to be replaced, types with a rubber exterior (type R or RST) are easier to fit. Type MST is similar to M and commonly used. The difference is the dust lip in the MST oil seal that prevents dust and dirt reaching the sealing lip, and extends its service life in dusty environments.
Foam inhibitors: This additive does exactly what it sounds like. Foam inhibitors keep motor oil from forming foam and bubbles. If foam and bubbles were to form, the oil would be unable to coat the important parts of the engine and keep it cool.
Oil seal WG1087811 is used by several automotive manufacturers, such as Opel, Fiat and Suzuki, and serves as a good example for an oil seal where oil leakage can occur if fitted incorrectly.

Oil seals operate by creating a tight barrier between two moving or stationary parts, such as a shaft and housing, to prevent oil from escaping and contaminants from entering the system. This is essential for maintaining the efficiency and performance of the machinery, as well as preventing potential safety hazards.