Oil works, but requires constant application. And it makes it tough for any paint or sealer later to stick properly. Drips from constant application will get all over the ground - it probably will be a concern for you.
There are all sorts of products a do it yourselfer can spray or brush on.
It's best to scrape, wire brush, and sand the rust until you get sick of it. [A perfect surface is not necessary.] Plain Rustoleum is very good - spray or brush. So are a dozen spray undercoatings.
Sure, touching up every year is going to be required, but it is much better than oil.
There are all sorts of products a do it yourselfer can spray or brush on.
It's best to scrape, wire brush, and sand the rust until you get sick of it. [A perfect surface is not necessary.] Plain Rustoleum is very good - spray or brush. So are a dozen spray undercoatings.
Sure, touching up every year is going to be required, but it is much better than oil.