Thanks for letting me a bit early gentlemen.  I learned from a local pressure washer that I befriended that aluminum brightener from our local supply house works better than their rust remover.  I have used it so far on concrete, vinyl siding, & painted wood. 

Remember, it's an acid, so keep it away from your bleach and wear gloves and glasses.  Also, rinse thoroughly after application.  I apply it with a two gallon pump up sprayer.  If this little tip helps anyone, feel free to use it.