It's a tiny little four cylinder Kubota Diesel with a few thousand hours on it. It runs just barely above idle. I don't like putting hours on a new machine, but at that age, and those few hours for splitting, it doesn't really matter that much to me.
I really don't like the sound of small gas engines. They are a wonderful source of power in a small package, but find them annoying. Especially their speed, which is what gives them such good power for size.