Now a days the underground tanks at the gas stations have automated monitoring systems. They have alarms on them that go off if the moisture in the tanks get close to the pump pickup. The pickup is mounted about 6 inches off the bottom of the tank so you will never get the sediment or water unless the tanks have been severely neglected. Also each pump has a filter in it that catches anything that may be floating around in there. You notice sometimes you have a pump running very slow? That means the filter needs to be changed. These stations also go out of their way not to run dry because they will loose sales if they do. I drove those big tankers for about 10 years so I know what I'm talking about on this. Generally if there is a problem with the fuel it was delivered that way and the problem came from the terminal. Around here most of it comes from the port of tampa.

Also don't get stuck on any certain brand of gas. It all pretty much comes from the same tanks. Shell, texaco, and marathon all come from the same terminal in tampa and the same tanks. The additive of the brand is shot into the tanker at the same time the fuel is. Also stay away from mid grade. It's cheaper to make your own. 65% reg and 35% 93 octane super gives you 89 octane. The tanker drivers generally mix it themselves when loading. There is no mid grade at the terminals only reg and super.

However......Top Tier Gasoline (top tier explained)
and
Top Tier Gasoline (top tier approved stations that meet the requirements)

Still the same stuff just with the brands additives.

Thanks for the info, omike. Things I never knew (or thought about, to be totally honest).