I bought a used OS60SF that had been in the box on the shelf for several years. When I finally decided to use it, it was pretty stiff so I filled a container with 15% fuel and just put the engine in there for about four or five days. When I pulled it out, it turned free without any binds. It now powers my Tiger 60 and runs very strong. Good engine, but, from what I could see, this was never stored with anything in it except the residual running oil that was in the fuel. That is not to say that I was not lucky nor to say that after-run oil does not help because I use it, about 6 to 10 drops after running the thing dry, put it through the carb and turn the engine over by hand a few rotations, close the carb (throttle to min with min trim) and, so far so good. Three of my engines have lasted through the winter months without any issues... that I can see, that is. I'm sure one of the backyard engineers on the forums will tell me different, though. Hey... Justin Wilson (chef and safety engineer) states that he is double safe.. both a belt AND suspenders. A tad bit of Marvel Mistery Oil never hurts.