“The Dee-Zol fuel additive was, to my surprise, a great fuel economy booster. As you know we have fourteen heavy-duty cranes, five tractor-trailers, and one service truck for which they all use the fuel treatment. This increased fuel economy up to 10% better and no more cold starting problems. The black smoke that used to pour out of the exhaust is gone. The engine runs so much smoother and no knocking and pinging inside the engines either. We used to go through so many fuel filters and now virtually none. Water and sludge problems were resolved without any repercussions. We thank you for making a great product. Without a doubt, your products work in all the applications we used them in.