I have friends who have backup whole house generators and they are set up to turn on and run once a week to confirm they are still online, and to keep them from having maintenance problems,. With my Yamaha portable generator, I've been told I should start it and run it once a month, preferably with something plugged into it to put a load on it. I try to do that, but have to admit sometimes a couple months will go by before I think to do it.