If you must use after run oil, it needs to go into the crankcase through the venturi. About a teaspoon full is about right. Be sure to remove the glow plug and run the engine with a starter for 10 or 15 seconds before fueling and running the engine again, otherwise it will be loaded up so bad starting will be a problem.

With YS engines, they must be completely dry before storage. Any fuel remaining in the regulator can cause problems. This is one of the reasons we recommend only synthetic oil fuels for them. Castor has a tendency to gum up the regulator during storage.

Good Flying,
Dave