Well let's just say this, there's really no reason to worry about fueling when or after the truck is there. There are BIG filters inline to catch anything before it reaches your pump. Also the gas will vary from time to time due to where it is loaded from. Price & supplier will change daily if not 2-3 times per day & dictates where & what grade of gas you are getting. Yes the government regulates the octane rating, but there are several blending techniques to come up with the same so called octane rating. Thus giving you different actual grades of gas depending on this method & supplier. I've hauled this junk daily for @ 9 yrs. If you only knew the behind the scenes. Also the time of year & where you live will dictate this. RVP pressure laws change in summer & the winter around big cities. You will notice big changes in fuel mpg then too.