Coat the sump flange with gasket-sealant and fit the flat parts of the gasket to it, ensuring that they are exactly positioned and joined.
Beyond the variety of lip designs, oil seals also come in various case designs, each serving a unique role. Here are some of the most common ones:

The basic principle of an oil seal is fairly straightforward. It is installed adjacent to the bearing, with the flexible lip against the rotating shaft and the casing pressed into the housing to hold the seal in place. It’s important that the sealing lip is lubricated to prevent it from overheating as a result of any generated friction. It’s also crucial to understand which type of seal is appropriate for your particular machinery. Before selecting your seal, consider the environment, temperature, pressure and shaft speed of your machine, as well as the type of medium the seal will come into contact with during operation. These considerations will all determine the size, colour, and type of lip material or sealing element to choose, and whether it can be sealed in or sealed out.
The block is unlikely to distort except after severe overheating, but check anyway using a steel ruler or similar high-quality straight-edge.