Try some meguiar scratch x. Then the final wax or polish. I agree with the Collonite or Zaino suggestions. A couple over the counter products that are quite good are Dura Gloss available at Car Quest or Liquid Glass available at most auto parts stores.
I picked up something from Ace Hardware last weekend to try out. It is a 4ft. triangular shaped piece of foam. The idea being it fills the gutter space so leaves can't fit in but water saturates the foam and passes down to the downspout. I was very pricey $10.00 marked down from $15.00 the guy...