There may be a rubber '0' ring oil seal round the base of the distributor, or a paper gasket under the plate of the securing clamp. Remove either seal, clean away all dirt and oil, and fit the new one.
C
Summary
Nitrile

Purpose of an Oil Seal
However, the new variant also comes with less good properties. Namely less flexibility and less resistance during assembly. Most damages therefore occur during the installation of PTFE oil seals.
Waterproof rubber gaskets are designed to provide a secure and watertight seal, making them ideal for applications where protection against moisture and environmental elements is essential. These gaskets are commonly used in outdoor equipment, marine applications, and electrical enclosures to prevent water ingress and ensure the integrity of the sealed components. The waterproof properties of rubber gaskets contribute to the reliability and longevity of the sealed systems.