A properly maintained generator should provide over 20 years of operation under emergency standby conditions. Keep in mind that the units are not intended to provide continuous power (24 hours a day, 365 days a year as a replacement of your hydro utility). On the other hand, we had several customers whose generator ran it for 5 to 10 consecutive days.
If you are thinking of using it for a "off the grid" cottage, we suggest you turn it on only when you need electricity, therefore also saving fuel when there is no electrical load.
We have a special 6kW for off grid that will start on demand only when batteries, solar, and other systems are not sufficient.