>
> Something pretty close to magical is electrolysis. Here is a page
> (http://antique-engines.com/electrol.asp) that describes how to do it.
> You just need a small battery charger, some washing soda and a
> container big enough to submerge the grates in -- say one of those
> plastic swimming pools for kids. The good thing about this technique,
> apart from not involving the elbow greese, is that it will get rid of
> the rust in all those hard-to-reach places that the wire brush might
> miss. I'd think it would take maybe a couple of hours in the solution.

A very easy to remove rust from the grates is to place them in a bath of
WEAK muriatic acid. This acid is available at most home remodeling stores
(Home Depot) Dilute the acid 50% and use rubber gloves. The acid will
dissolve the rust off COMPLETELY. Be sure to rinse the grates VERY GOOD.
After they are relatively dry, put some cooking oil over ALL SURFACES.