High-temperature aging and deformation of hydraulic pump shaft oil seals is a common failure mechanism in industrial fluid power systems. When the sealing lip is continuously exposed to elevated temperature, the elastomer undergoes thermal oxidation, molecular chain degradation, hardening, and permanent set. These changes reduce the seal’s ability to maintain consistent radial force against the rotating shaft. At the same time, heat generated by friction and inadequate lubrication can accelerate lip wear and increase the risk of groove formation on the shaft surface. Thermal expansion differences between the metal housing, shaft, and elastomer body may also change installation stress, resulting in distortion, warping, or lip instability. Once deformation appears, leakage pathways develop quickly and the hydraulic pump becomes vulnerable to oil loss, pressure fluctuations, and contamination ingress. Understanding the high-temperature failure mechanism is essential for correct seal selection and system optimization. Industrial seals made with improved heat-resistant materials, precise dimensions, and stable lip geometry can help hydraulic equipment maintain durability, reduce maintenance frequency, and perform more reliably in high-load, high-speed, and continuous-operation applications.