ok, so i think our siding is made of aluminum..some of the siding looks like it just may be dirty and just needs a powerwashing, but some of it, like where bushes used to brush up against the house, has striped away the "powder" (which comes off if you rub your finger across it) and left it looking bare and silvery
pic of where the bushes rubbed off the 'powder'
pic of where i think it may just be dirty
what should i do??