I think it has to do with how it’s dispensed. If the person before you bought regular fuel, the hose still might have residual fuel from the other kind, meaning you could end up with a different ethanol level than expected. That’s a fire hazard. 4 gallons is probably overkill but better safe than sorry.
Edit: basically, if you accidentally get half a gallon of 10% ethanol fuel and half a gallon of 15% ethanol fuel, you actually have 12.5%.
E15 is available in 31 states at just over 3,000 stations. E10 remains the limit for passenger vehicles older than model year 2001 and for other non-road and small engines and vehicles that use gasoline, such as lawn mowers, motorcycles, and boats.
I think it has to do with how it’s dispensed. If the person before you bought regular fuel, the hose still might have residual fuel from the other kind, meaning you could end up with a different ethanol level than expected. That’s a fire hazard. 4 gallons is probably overkill but better safe than sorry.
Edit: basically, if you accidentally get half a gallon of 10% ethanol fuel and half a gallon of 15% ethanol fuel, you actually have 12.5%.
Has that always been the law and I just never noticed a sticker like that before?
Not sure how long it’s been a law but not a ton of places sell E15. I only ever see it on road trips personally.
https://afdc.energy.gov/fuels/ethanol-e15