Leakage caused by high-temperature aging and deformation of hydraulic pump shaft oil seals is a frequent issue in industrial hydraulic systems. The shaft seal is responsible for retaining hydraulic fluid while preventing dust, moisture, and particles from entering the pump housing. Under elevated temperature, however, the elastomer can gradually degrade through thermal oxidation, hardening, softening, and permanent set. These changes reduce the sealing lip’s flexibility and contact pressure, making it more difficult to maintain an effective barrier on the rotating shaft. Frictional heat, poor lubrication, shaft eccentricity, pressure fluctuation, and contaminated fluid can intensify the problem. Once the oil seal deforms, leakage paths develop more easily and fluid loss can increase rapidly. This not only affects hydraulic efficiency but also raises maintenance cost and the risk of unplanned shutdown. Preventing leakage requires industrial seals with suitable heat resistance, accurate sizing, and reliable oil compatibility. Good cooling, shaft surface control, and correct installation further improve performance. In hydraulic pumps used for construction, heavy industry, agriculture, and manufacturing, dependable industrial seals help reduce high-temperature leakage problems and support longer service life, more stable pressure, and better system reliability under demanding operating conditions.