The Penray Pow-R 3655 in 1 Diesel Treatment is a versatile blend of additives and conditioners that is designed to improve fuel economy and engine performance. According to the company, the diesel treatment increases fuel cetane rating by a full point, making for improved combustion. It also helps increase fuel economy, protects vital fuel system components, enhances lubricity and provides protection down to zero degrees F. Sold in 64-oz bottles, each bottle treats 250 gallons of diesel fuel.