How to preserve cast iron seals from the old westside highway?

Hi, we own a collection of the former seals on the West Side Highway, which are made of cast iron.  Over the past 2 weeks or so, we're noticed they've begun to decay.  Does anyone have any suggestions for how to save, as it would be a shame to let apiece of history go to ruin.  Any advice greatly appreciated.   They are shown here: http://www.smpub.com/ubb/images/09/nycseals.html 
 

petercd3 years ago

When you say decay do you mean rusting?

Id probably then derust and once dry spray them with an automotive clearcoat.