As both of my generators are mounted systems, one an Onan 2800 and the other an Onan 7.5kw. For the big moho with the 7.5kw genset, I put an adequate amount of Seafoam in the vehicle's gas tank, and run the generator for an hour or so to make sure that the Seafoam makes it through the genset's systems before I store the moho for the winter. The B-van, I just run regularly, and I run enough gas through it that it doesn't sit and get stale.