I sandblast then wipe down all areas with a compound like jasco metal etch or any others than contain phosphoric acid (naval jelly does too I think). Phosphoric acid chemically changes the iron oxide into another compound that is relatively inert. I finish off the surface with a two part...
If it is not in a visable area you might try either coldgalv or rustoleum rusty metal primer, and put on several light coats to insure it is well sealed.
Methalene Chloride is a great cleaner degreaser and is not explosive as a vapor. The fumes are toxic as are most of the others, however this stuff disolves so well that most of the time a good soaking and a quick brush off is all that is required. Makes short work of cosmolene too. It evaporates...