Rust inhibitor

I'm trying to bring an old steel tubular exhaust manifold back to life after it has been sitting in my garage rusting away. I've got rid of most of rust by acombination of rust removing chemicals and some rubbing down. When I get it all nice and shiny again I would like to apply something to stop it rusting over again (it is not going to be fitted to a car right away) that is also heat proof and still leaves it looking like metal (i.e not paint). Can anyone recommend a substance that can do this?