I have GENERAC 5.5. Four years ago the main oil seal went bad and I had oil all over the thing.
Took it to a shop that does this kind of work and they told me the unit would have to be removed, rebuilt and re-installed. MAJOR work.
Watching them do the work, they used a fork truck to remove the unit and also to put it back in. Then they fixed the problem and that needed a complete tear-down to get TO the seal. $2400. They assured me that after all was said and done I would, for all intents and purposes, have a brand new generator. Well, so far, so good. Cost effective vs a new one? I think so.......