I see quite a few comments above that I take issue with. First off, anytime you use an alcohol fuel or any fuel with nitro in it, you will always benifit from using after run oil, not just a drop or two but about a teaspoon full in the crankcase whether a 2 stroke or 4 stroke (of course you must put the oil in the breather tube on a 4 stroke, into the exhaust or carb will do little good). Any residual alcohol will attract water--i.e. rust-- and any nitro residue will tend to form an acid which can do a nice etching job on the innards of your engine. If you are using just a drop or two of after run oil, you are only deluding yourself as to any help you are giving the engine. Use Rislone (in the yellow container) or ATF (automatic transmission fluid) for an economical after run oil. Any air tool oil will also work well. While Marvel Mystry Oil is better than nothing, it is not as good as Rislone or the other air tool oils, especially for long storage.