guys turned on the lawn sprinker system for the first time at start of Spring time several years ago. Happened to be a very warm day and the sun baked that scummy old, stagnant water and contaminants right into the black paint. I tried to rub it out using a Turtle rubbing compond and really screwed up the finish (swiral surface marks in the wax finish)!!!!! I ended up taking it to a professional for a buff job that cost about $125.00. Turned out real nice. Lesson learned (avoid the Plant sprinker systems).