I rarley ever use after run in mine. only if they are going to be sitting but I especialy use after run if I was running in wet conditions or if its going to sit in the garage when its damp in there. I always make sure my piston is not at top dead center after I run it. I use marvel mystery oil for afterrun. Good stuff.. much better imo that WD40 because the marvel is thicker and seems to coat everythig inside the engine very well. Also most of the RC after run oils are marvel oil anyhow. Hobbico after run, racers choice after run.. its all Marvel oil.