Drivers who filled up at a Holly Springs gas station late last month may want to pay close attention to how their vehicle is running. Inspectors also found “phase separation” coming through the premium fuel pump, meaning there was water in the fuel. The water and ethanol separate from the gasoline, creating a caustic mixture that can damage vehicle fuel systems and engines. Because the station's mid-grade, or "plus," gasoline is created by blending premium and regular fuel at the pump, the contaminated premium fuel also affected the plus-grade gasoline. As a result, the state ordered sales of both premium and plus gasoline to stop.