I use mine all year round. I think/hope, if protected, Waxoil, etc and hosed off, dirt scraped from known mud traps after winter (roads not salted much here), Try and avoid water entering floors, deck, boot, then okish?.
Back in the day, most of these motors were neglected body/chassis wise, did higher mileage in wet, more salty conditions. Not surprising they were rust buckets after 10 years or so I imagine?.
Dave