I been running Marathon gas for several years now until today. Yesterday my favorite fuel station had bags on all their pump nozzles so I had to go down the street to a Chevron station. Pumped in $40 worth and went home. This morning I had to go back into town and do some running around. I drive like I wanna get there so I'm usually on the go pedal,MPG be damned. On the way back a slow poke jumped out in front of me so the first opportunity I got I mashed the motor. I was running about 40 and it lit the rear tire and shoved me in the seat when it grabbed back up. Ol Smoky has never run that good and after putting about 30 miles of cruise and stop and go the fuel gauge was reading the same as when I left the house. I don't know if it's all Marathon stations or just the one I usually haunt but there is definitely a difference in the amount of pop in the fuel.