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.