My mower and edger run 1.5 hours per year each. Winter maintenance consists of ignoring them. Following the B&S instructions would mean an oil change for each every 33 years, but I'll probably do it more often than that.
So far as fuel is concerned, I ensure there is no ethanol in it, and don't worry about how old it is. The last six months or so I've been using a jerry-can of red petrol that a guy gave me, saying it was "very old" and he didn't know if it would be any good after all this time. Seems to be winter fuel - higher vapour pressure than summer fuel - but otherwise indistinguishable from modern unleaded. I do remove all fuel from my line trimmer (because it is a two-stroke) and my spare mower (because hopefully it won't be used for ten years or more). I also gave the spare an oil change immediately before storing it.
