PTFE is special in that a pre-tensioned spring is not required. This is because the material returns to its original shape when heated, also known as the shape-memory polymers (SMPs) effect. These oil seals are also supplied as integrated parts, where it only needs to be installed as one component.
Table 5: The major special seals, their shapes, and their features
One of the main causes of black spark plugs is a rich air-fuel mixture. This means that there is an excess of fuel in the combustion chamber, which can lead to incomplete combustion and the production of carbon deposits. A rich air-fuel mixture can be caused by a variety of factors, including a faulty oxygen sensor, a clogged air filter, or a malfunctioning fuel injector. It is important to address these issues promptly to prevent further damage to the spark plugs and the engine.
black spark plug

This is a specific type of synthetic rubber that’s commonly used in o-rings, gaskets, oil seals, sterile & chemical resistant gloves, and other molded items. Viton has a high density and it possesses the widest temperature range of -40 degrees Fahrenheit to more than 400 degrees Fahrenheit. This is why it’s highly preferred as the best material for higher temperature applications.

Loosen the securing-clamp bolt at the base of the distributor, then carefully withdraw the distributor.
Renault/BPW
For more detailed information, please see the following:
Names and functions of seal components
Despite being incredibly flexible, silicone has some significant drawbacks. The toughness, resistance to wear, and abrasion of many silicone compounds are poor. If you seriously need an oil seal material with better strength and resistance to high temperature, the perfect option is Viton.