Ok, follow me on this one. Here’s the scenario. You leave home to head on a decently long road trip with the family. As soon as you hit the road, the kids complain that they need to use the bathroom. We’ve all been there. So, you pull into the nearest convenience store or gas station and figure, “I’ll top off my tank while I’m here. Might as well.” So, you reach for the cheapest gas available and manage to pump just short of 4 gallons. And that’s when you break federal law. No, I’m not kidding.
So now you’re asking yourself, “How in that scenario am I breaking any laws?” I get it and I’m with you. I wouldn’t even have known if I didn’t read the gas pump this morning and then do a little research. Let me break it down for you.
At pumps across the United States, you may notice a little sign at the pump that says, “if you pump less than 4 gallons of gas — specifically E-88 — you may violate Federal Law. So, it’s a combination of both the type of gas you’re pumping, the style of pump you’re at, and the amount of gas you pumped.
The minimum 4-gallon purchase requirement at some Iowa gas pumps for E88 (also known as Unleaded 88 or E15) is primarily due to concerns about residual fuel left in the pump’s dispensing system. Fuel pumps that dispense multiple fuel types through a single hose (like at many Casey’s) can retain a small amount of the previously dispensed fuel—typically between 0.1 to 0.25 gallons. If a customer dispenses a small quantity of fuel, this residual can significantly alter the ethanol content of the fuel entering their vehicle.
Credit: Canva Heres an example of a single hose fuel pump. Multiple types of fuel, but only one hose to fill with…