Material used, oil type and temperature of lip part largely affect the life of oil seal.
In particular, life of oil seal shortens with increase in temperature.
The following graph shows temperature of lip sliding part and life of oil seal.
For example, nitrile rubber seal used in gear oil deteriorates in about 9000H at 60°C as against about 1500H at 80°C.
Oil seal deterioration causes oil leakage and its restoration work causes time loss. Furthermore, calling a special maintenance in-charge requires cost of <charge unit x working hours x number of working people>. When actual work of machine is taken as 8 hours daily and 355 days annually, it becomes loss of about 500 ℓ in a year if 1 drop (about 0.05 cc) leaks in 1 second.