I have a 2014 Silverado and was talked into this Enviroguard product which is supposedly guaranteed for 7 years. My truck is parked outdoors in a wooded area and I was told this product would repel anything. Well - I have black dirt spots on the roof and hood that I can't get out using things like hot water and dawn. Does anybody know of a chemical or specific product I can use that won't damage paint or this SUPER Enviroguard?

Thank you

Joe C.