Just like pressure. The temperature capability of the oil seal shouldn’t be lesser than the temperature of the application. This is because any significant increase or even decrease in the temperature will affect the functionality of the oil seal. PTFE seals have the highest temperature capability, making them useful for applications that demand harsh weather and elements.
Leather oil seals are commonly used for parts that are exposed to dirt and poor lubrication. The major advantage of this material is that it can function in cases where synthetic rubber cannot function. They are used for shafts that have rough surfaces that are more than what rubber seals can handle. This is because they are pre-lubricated and have the capacity to absorb liquids.