You mean after run oil, nope, never. If you do a search there are several links talking about it. I only have a problem with old hardened castor with engines I have left under the bench for a very long time, sometimes years. If I had ran them dry after use they always seem to be OK, if the engine/plane was in a crash or something then they tend to be hardened up and I use a heat gun to loosen them up then just fire them up and use them. RUST!! I have never had a rust problem either. I think that is because of the climates I have lived in, almost no humidity. If I lived in the mid west and I wasn't going to use my engines for a long period of time I think I would run them dry and use some after run oil but it's hard to get the stuff into the bearings where you need it. It doesn't hurt anything to use it so if you would feel better using it give it a try. Just type in After Run Oil and see what people think about it.