Oxalic acid will diminish rust spots, however, if the surrounding areas are not nice & bright, you will need to treat all of the surface. It's not real great as a spot treatment. Your rusty spots will be nice white spots compared to what's around it.
One important thing to mention about oxalic, particularly since there are so many "younguns" on this bbs.....oxalic acid can cause sterilization. If you still want to reproduce, please please use the proper PPE when messing with the stuff.
Celeste