Out of all of the elastomers, silicone offers you the widest range of working temperature ranges. Renowned for its flexibility and low compression set capabilities, silicone is the optimal choice for o rings and other moulded seals.
Material Selection:
Maintenance and Replacement of Spark Plugs
An oil seal consists of:

steering oil seal.
Polyacrylate is a great compromise between cost and quality. It has a high performing temperature and chemical range, but not to the extent of the range of Viton. The temperature ranges from 31°C to 148°C (-25°F to 300°F). Polyacrylate is primarily used in automotive transmissions and hoses but also found in shaft seals, gaskets and o-rings, due to offering a high resistance to hot oil and oxidation. While Polyacrylate is a great alternative to other high temperature resistant materials that are more expensive, it does have a poor water compatibility and cold flexibility. The best situation for Polyacrylate is an environment where heat and oil resistance but cost is the major issue. And while these 4 different materials cover a wide range of applications, there are even more materials out there designed for very specific niches in mind.

m20 valve cover gasket.
VMQ, also known as silicone, is also used for oil seals, but this is less common because the mechanical strength of VMQ is low and this material has poor wear-resistance This makes it less suitable for dynamic applications, but it can withstand fairly low and high temperatures from -60 °C to 200 °C. Many types of VMQ are also suitable for contact with pharmaceutical and food products, so VMQ is an option worth considering. VMQ oil seals are usually available on request.
Regular inspection and maintenance of valve cover gaskets, head gaskets, and spark plugs are essential to identify signs of wear, damage, or deterioration. Proper replacement of worn or damaged components is crucial for maintaining the efficiency and reliability of the engine. Adhering to recommended service intervals and using high-quality replacement components are essential for optimizing the performance and longevity of the engine's critical components.