FWIW - on the Stanadyne website, there's an asterics next to "One Shot" which states - *Special formulation ratio for "One Shot" application. [To treat 15 gallons of diesel with the recommended doseage of SPF you just need 4oz. from either the pint or 1/2 gallon containers.
Shop Stanadyne Performance Formula Fuel Additive 38565 for the For use with all diesel engines, 1 - 16oz. Bottle (treats 60 gallons) . XDP carries all the parts and accessories you need for the best diesel performance.