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Requirements of the shaft
Even more important than a correct interference fit of the Oil Seal is a perfectly smooth shaft in the region of the seal, particularly if shaft surface speed is high and the medium to be sealed is under a certain amount of excess pressure. The surface roughness of the shaft depends on the average profile depth Ra of the tool marks caused by the machining process. Oil Seals made of PTFE require, independent of the surface speed, a surface roughness of between 0,1 to 0,2 mm, because PTFE has less wear resistance than rubber seals. For normal circumstances, the shaft in the region of the seal must have a surface roughness of approximately:  To summarize, the surface of the shaft in the region of the seal should not have noticeable machining marks. For pivoting shafts and other difficult or critical sealing applications, it is recommended that Oil Seals with a helical groove hydrodynamic pattern, which has a pumping effect, be used. When grinding and polishing, an axial movement of the grindstone along the shaft must be avoided in order to prevent machine lay. 

Oil seals are used in a great many devices for steel production equipment.
Figure 7 shows the places where each seal type is used in a rolling mill.

Figure 8: Shaft runout

A synthetic rubber used in gaskets, o rings, lip seals, and other moulded devices, Viton offers sealing properties for a range of oil-based applications.  Viton with high fluorine grades will also produce excellent resistance to swell, especially in oxygenated fuel and high-octane blends.