I collect cars, trucks, airplanes,and boats. I have started gasoline engines that have set 30 years in a field under a closed hood and only had to clean the carburetor and they purred like a kitten. I once cut a tree out of the engine bay of an airplane,started the engine and took off. (I will admit when I was in my 20s I was a damned fool idiot.....) Diesels in a mild climate in the interior of a closed boat will restart after at least 5 years and run like it was yesterday they last ran.
BUT were they damaged internally by the neglect? Maybe, but I never saw evidence of it, even in the airplane engine with the tree in the cowl. But I dont recommend neglecting the engine, but changing oil before storage of a few months isnt required in my opinion.