When should the piston and ring assembly be installed into the cylinder?

The piston and ring assembly should be installed into the cylinder after coating with motor oil because this step is crucial for ensuring proper lubrication during the initial moments of engine operation. When the piston and rings are coated with motor oil, it helps reduce friction and wear during the critical break-in period when metal surfaces are coming into contact for the first time. This oil film assists in protecting the components from potential damage due to dry starts and helps in sealing the combustion chamber effectively.

Applying motor oil not only aids in lubrication but also facilitates the installation process by making the rings slide more easily into the cylinder bore. Proper lubrication is vital in enhancing the longevity and performance of the engine. Installing the piston assembly without oil leads to increased friction and could potentially cause premature wear or failure of the piston rings and cylinder walls.