[Michael Kilduff]

POR-15 will do a good job in arresting the rust. I used it as a rust preventer on an old camaro that has sat outdoors for 6-7 years and hasn't rusted even a bit.

For a large area like the frame (I would do the floors too) you will want to clean it the best you can and have a body/paint shop spray the whole underneath. If you do it yourself-and POR-15 isn't all that expensive- take precautions as I think it is very toxic, so I was told when I used it.