Just a word about additives. I communicated with an engineer at Stanadyne about additives, and have done some research about it. He said that they have been making their additive and improving it since the late 70's, early 80's. They make fuel injection equipment, and know how to protect it since fuels have changed and sulfur content has been mandated lower for emissions. I have used the Performance Formula since the early 80's and have operated several near 200,000 mile vehicles without a fuel pump failure! I know it works! This additive is one of the few endorsed and recommended by Ford, GM, Navistar, Deere, Caterpillar, VW, Volvo Penta, and AM General. Short term improvements don't mean much with fuel additives. Longevity and protection are the keys. These can't be measured in quick terms. Good luck!