The purpose of any seal is to protect a joining in a piece of equipment. Seals serve to keep lubrication or other liquids inside and contamination outside of the joint. A lip seal is also known as an oil seal or a rotary shaft seal. Oil seals or rotary shaft seals and mechanical seals are designed for moving parts. So how do you decide on an oil seal vs mechanical seal? It helps to understand how they are similar and how they are different. And of course, the precise needs of the application are really the deciding factor. They are designed to endure the strain of continuous movement in an environment where they are exposed to contaminants such as grit, dust and dirt such as hydraulic pumps and valve stems. Typically made with various types of rubber, oil seals are sophisticated and varied to suit a range of applications. Some are spring loaded; others are not. Oil or Rotary shaft seals are vulnerable to extreme temperatures, which can cause them to wear out faster if they are used in very high or low temperatures. A mechanical seal features stationary elements, rotating components and a spring. It is a complex piece of equipment, and the type of spring varies depending on the needs of the specific application. It is the interface between stationary and moving parts of machinery. It serves the same function as gland packing, but is significantly more durable and requires less maintenance. Mechanical seals are used in applications with a rotating shaft. One of their key benefits is that they are relatively low maintenance, which improves productivity.