What can be used after cleaning vinyl siding?

[deltadart]

I'm here in Cedar Rapids Iowa where we had a terrible flood. Although my house was safe the vinyl siding is very dirty from all the dirt that was in the air. My siding was dirty to begin with but now it's worse. Soap and water will not cut the dirt and the only thing that will is a very time consuming scrubbing using paint thinner. What I need to know is there something(Armor All?)that I can put on the siding after I get it cleaned that won't allow the dirt to adhere to the siding? I realize it will get dirty but it would be nice to be able to wash it with soap and just rinse it off using the garden hose. Thanks!