We use the 5500 running straight for long weekends with no issues (other than bad electrical connections). We maintain it well, use it frequently, and it has been rock solid. Not even a hiccup. Ran in 95 degree heat at heavy load (both A/C units and my mobile kitchen) for three days straight. Diesel could probably last 10-15K+ but i would not expect gasoline to last more than 5-6K hrs. I have heard (in forums) of people with 7,000+ hours but I'm not sure I would trust it at that point. For my use, 6K hours would mean 12 - 14 years.