As a farmer for 45 years we always had equipment set during the winter. I use to go through the barn and charge batteries once a month. Later we started irrigation which required more winter use. However: either way the engines never hurt. One irrigation engine that set for months,(diesel), just got pulled odd with about 60.000 hours. One thing I think is very important is to keep tank full and a good fuel additive in tank while setting. Thus water is controlled and fuel does not get so old. Right now I run a 6.7 Ford, which I leave in barn during the winter. Does not hurt the engine.