If it is stored inside, the moisture levels are much lower than if it was outside. So if it has been sitting less than 6 months, it is probably fine. Crank it over once in awhile, to take the load off of valve springs, which will also open a different cylinder to the air. I have several vehicles I run through the winter, off and on, and after 20 years I have had few issues. The biggest are usually fuel related, not with the block or oiling. This new gas sucks, and sitting can really cause problems. There have been numerous threads on sta-bil etc., (which I use) but as far as harm to the engine from sitting a few months? Don't worry about it, run it and drive it as often as permissable. Here is a test I did in the past, when I was worried about similar things.........I took a bare piece of sheetmetal, and stuck it under the hood of a car to see if it would flash rust. It never did, in like a year.........God, I love my shop!