Choosing Quality Oil Seals:
JTEKT provides special seals for use in a wide variety of machines and applications.
Table 5 lists the major special seals, their shapes, and their features.

0.1 to 0.32 μmRa and 0.8 to 2.5 μmRz
and the lead angle to no greater than 0.05°. (There is a risk that the lead marks will impede the sealing performance of the oil seal: see Figure 5.)