Tank Shield is a fuel additive that keeps fuel oil tanks, burners, and stoves trouble free and extends their life. Tank shield will dissolve gum and sludge deposits and conditions the tank to keep condensation from forming, protecting against rust and corrosion. Add to your fuel tank before filling for the best results. Not for use in unvented kerosene or oil heaters, fireplaces, wood or coal stoves, or furnaces. One quart per 250 gallons of oil for the first treatment, one pint per 250 gallons thereafter.