AS a licenced tech, I'll throw my 2 cents in. Even though our engines work harder than if they were in cars, for the most part, they don't have enough hours after one season for an oil change. However, once engine oil is put into service and begins it's life, it now has time factors. Where I live, the time factor requires 1 oil change per year. I do mine in the spring and after a few hours running time. 2 reasons for this. First one is, the final thing most people do is fog. This will burn way beyond rich and contaminate the new oil somewhat. I wouldn't want that somewhat contaminated oil being pumped through my main engine bearings all next year. Second thing is condensation. I prefer to have any winter condensation get dispersed into the vents and into the oil ( as it's engineered to) and then changed taking all the winter guck with it. This way I know I have nice clean and fresh oil in for my season.
My fogging technique is a bit elaborate but here it is. Once I've winterized the cooling system, I pull the spark plugs and fog each cylinder induvidually with ONLY synthetic. Synthetic wont build up underneath the piston rings as sludge over the years and eventually break them. Then with all cyliners fogged, I crank the engines for 2 or so seconds each, coating the cylinder walls and valve faces and seats well. Slap the plugs back in and it's all over but the crying. Nothing above the intake valve needs fogging so having my engines breathing it only gunks things up. Also with sythetic, I never have a starting issue. They fire up like they were shut off yesterday and NO blue smoke either
John