Standard springs are made of carbon steel. We use stainless-steel springs for our GR and GRST oil seals made from FKM rubber. In some rare cases, an O-ring is even used as a spring element. Standard PTFE lip seals are not fitted with springs.
Please see the following for the types of sealing devices for bearings.
How to Select the Right Bearing (Part 7): Components surrounding the bearing
There are four general motor oil types:

U-shaped silicone gaskets are versatile sealing components used in various industries for their resilience, flexibility, and resistance to extreme temperatures and environmental conditions. These gaskets are commonly employed in applications where a reliable seal is required, such as in automotive, aerospace, and industrial equipment. The U-shaped design allows for easy installation and effective sealing, making them suitable for a wide range of applications.
As shown in Figure 1, sealing devices come in two types: contact and non-contact.
Oil seals are among the major contact type sealing devices.