a)
Oil seals, also known as rotary shaft seals or lip seals, are a specific type of gasket designed to prevent the leakage of oil or other fluids in rotating shafts.
These seals are more commonly used in pumps, motors both electric & hydraulic, gearboxes & occasionally dirt wipers in hydraulic cylinders. They help protect shafts and bearings from dirt and harmful contaminants entering the internals of the application that they are fitted to, as well as prevent any leaks of lubricant.

Lubricant can be retained in the space between the main lip and the minor lip.
If you use accessories such as installation tools or grease containers, it is just as important to ensure they are taken care of. A good practice is to cover grease containers with a sealable lid when not in use. In doing so, you reduce the risk of dirt contaminating the grease and, subsequently, your oil seal.
contaminated with moisture or any other particle. But the same oil will only last for a month at 212 degrees Fahrenheit if it’s contaminated with little water. This is why the function of an oil seal is very evident whenever it’s used.
Polyacrylate
Better heat, oil and chemical resistance than NBR
It is recommended for use in oil which contains load bearing additives such as EP gear oils
Replacing the fuel-pump gasket
Duplex Oil Seals