When I cleaned the tank on my generator, it was almost certainly the first time in its life. It is a portable lighting unit with the lights and boom removed. For the 20-ish years before it became mine it sat beside another unit in the back lot at work. They were almost never used. I'd bet it was only since around 2010 that it had biocide added to the fuel. It's a wonder there wasn't more glup in the tank.
