The is a guy here who posted an oil analysis of Mobil 1 from his generator after a couple years and it was fine. My own feeling is a good oil will last more than a year under low hour use. But that is based on any usage run long enough in warm enough conditions to drive moisture out of the oil. Here in so. CA that is easy enough to do. Analysis is reasonable so you could take that path. Or just change it-easy and cheap.
Personally I use Mobil 1 0W40, run my exercise under load in warmer weather, and drain it every two years or so (at low hours).