Stanadyne Performance Formula (R) Diesel Fuel Conditioner is shipped by the case of 12. (stock No. SP38565). It is an all season diesel fuel conditioner, multipurpose fuel additive which tackles any diesel fuel related problem. Stanadyne Performance Formula is a diesel fuel additive which upgrades and stabilizes fuel by reducing sludge and fuel tank contaminants; cleans and protects fuel system components; removes varnish and other deposits to prevent plugging; increases power and fuel economy with cetane; protects against low sulfur fuels to reduce wear; protects against corrosion with an alcohol free formula; helps remove water from fuel; and provides hot and cold weather protection. It has been tested and approved by engine and vehicle manufacturers since 1993. Ford, General Motors, Volkswagen, John Deer, Caterpillar, AM General and others have recommended using Stanadyne Diesel Fuel additives in their engines and vehicles. One bottle holds 16 ounces, enough for treating 60 gallons. We highly recommend Stanadyne Performance Formula Diesel Fuel Conditioner and have used it for many years. Our 1990 3/4 ton Ford diesel pickup purchased new is still going strong. Weight of one case of 12 plastic bottles is 14 pounds.