As the sump level decreases, the life of the seal decreases. This can be explained through thermal analysis of the seal contact region of the shaft. Figure 4 shows the isothermal region at 1/2 shaft sump level. This is a good example of how the sump level affects the underlip temperature. Lubrication is a critical part of the seal’s cooling system and should be continually monitored. When sump levels are not adequate to cool the seal, special lip materials such as PTFE (Teflon) should be considered.