There is a British Standard laid down for the control of synthetic rubbers. BS 3574 (1989) helps to determine shelf life – for instance, Nitrile (NBR) and Polyacrylic (ACM) are Group ‘B’ rubbers and have a 7-year life, whilst Silicone (VMQ) and Fluoroelastomers (Viton®) are Group ‘C’ rubbers and have a 10-year shelf life. PTFE and Leather do not come into this category but like the others should be kept in the original packing for as long as possible away from direct light, dust, and humidity. Ozone, which can also be produced by battery-driven forklift trucks has a very bad effect on synthetic rubbers. Finally, protect the sealing lip – DO NOT hang the seals on nails, wire etc.
Remove the distributor cap . Before removing the distributor (See Removing and refitting the distributor ), mark the position of the rotor arm so that you can refit it just as it was.

318 valve cover gasket. The old gasket must be carefully removed, and the surface of the valve cover and cylinder head cleaned before installing the new gasket. It is important to torque the bolts to the specified requirements to ensure a proper seal and prevent any leaks.
Oil Seal Manufacturing: Processes and Considerations
Just like pressure. The temperature capability of the oil seal shouldn’t be lesser than the temperature of the application. This is because any significant increase or even decrease in the temperature will affect the functionality of the oil seal. PTFE seals have the highest temperature capability, making them useful for applications that demand harsh weather and elements.