Drivers using blender pumps that dispense both E10 and E15 fuel must purchase a minimum of four gallons per transaction. This requirement is a safety guideline established by the EPA in 2011 to protect engines in older vehicles from high ethanol concentrations.
The rule addresses the issue of residual fuel left in the hose and nozzle after a previous transaction. When a driver selects E10, up to one-third of a gallon of previously dispensed E15 can remain in the line and enter the next vehicle's tank.
By requiring a four-gallon minimum, the system ensures that the E10 fuel sufficiently dilutes any residual E15, preventing potential engine damage. Blender pumps operate by mixing gasoline and ethanol from separate underground tanks based on user selection.
These dual-purpose pumps are relatively rare, with approximately 200 locations nationwide out of more than 120,000 total gas stations in the United States. Many stations also offer E85, which contains 85% ethanol and is limited to specific flex-fuel vehicles.
