RE: After-run oil question
It is always best to run the engine dry at the end of your flying session. Just pull off or pinch the fuel line with it running and then keep starting it untill it will not fire any longer. This practice alone will help a great deal in reducing the corrosion / rust inside an engine. Then add your after run oil.
I have found that hobbico after run oil is nothing but marvels mystery oil and that stuff is not intended to be a rust/ corrosion inhibitor. My personal favorites are Air Tool oil (any brand) or Rislone engine treatment. Both can be found at any car parts store or even walmart. If you need an all synthetic after run oil if you are running a YS or other engine with silicone parts, the Castrol Syntec 0W-30 (the stuff made in Germany, not the rest of the syntec line) found at AutoZone is an excellent choice as is Red Line Motor oil.