The only gen-set I have is on my boat. It is 1967 Kohler 6.5 with about 3000 hours. If it gets started it runs for at least 30 minutes with at least 1000 watts of load. I have helped friends with newer gennys get through the anchor period by taking an extension cord to their boat. The old 4 banger Kohlers were and are very forgiving. With any newer genny I think I would be making sure fuel was fresh, carb was dry when shut down, in line shut off valves are cheap, and when run the load was 50% or more and duration lasted long enough to get the oil at operating temp for at least 15 minutes to assure condensation was eliminated (not only in the oil but in terminals, switches and associated spaces).