4 Bottles of Stanadyne 38564 Performance Formula 8 oz Diesel Fuel Additive Meets all fuel system requirements regardless of make, model or year For all diesel powered engines. Specifically formulated to provide peak performance in both hot and cold weather. This is a year-round product. Increases Horsepower - with up to 5 point cetane gain to improve combustion, resulting in better acceleration, power and torque Reduces Fuel Consumption - independent tests show gains up to 9.6% in MPG Easier and Faster Starting - in all conditions