When you are putting after run oil in it, are you putting it in the breather nipple on the bottom of the engine or on the glow plug hole? On a 4 stroke, it needs to go in the breather nipple. Something else that I do after I'm done, is I'll stick a piece of fuel tubing over the nipple with a plug in the other end. If there is a piece of tubing over the nipple anyway to direct oil away from the plane, just stick a plug in it. This will help keep oil from dripping out, and will help keep moisture out. That's what I do, and I haven't had a bearing go bad yet in an engine that I've been the only owner of.