Knocking on 91
Thread Starter
Intermediate
Joined: Jan 2009
Posts: 36
Likes: 7
From: Los Altos CA
I was under the impression that gas was gas. For the most part.
I saw a Modern Marvels episode that explained that all refineries created gasoline to a standard mixture. That mixture depends on the location and time of year. All refineries, whether they are Valero or Shell owned, 91 octane or diesel, pump gas into a common pipeline that distributes that gas to distribution centers near where the gas will be delivered. Once Shell dumps gas into the pipeline, they can extract the same amount from the pipeline at their distribution centers. The gas takes some time to travel in the pipeline, so the gas that the Shell distribution center takes out, may not be from a Shell refinery. It could be from a Valero refinery. Because it is a common formula, it doesn't matter. Once at the distribution center, Shell adds their formula for additives and then puts it in trucks to ship to local stations. But, since the gas is all the same, and the additives all do essentially the same thing, where you get your gas from doesn't matter.
The particular station may matter because it could have bad tanks with water in them or dirt, but the actual gas they sell is pretty much the same regardless of where you go.
I've experimented with different stations and it doesn't seem to change anything. I haven't used additives yet. That is the next step i guess.
I saw a Modern Marvels episode that explained that all refineries created gasoline to a standard mixture. That mixture depends on the location and time of year. All refineries, whether they are Valero or Shell owned, 91 octane or diesel, pump gas into a common pipeline that distributes that gas to distribution centers near where the gas will be delivered. Once Shell dumps gas into the pipeline, they can extract the same amount from the pipeline at their distribution centers. The gas takes some time to travel in the pipeline, so the gas that the Shell distribution center takes out, may not be from a Shell refinery. It could be from a Valero refinery. Because it is a common formula, it doesn't matter. Once at the distribution center, Shell adds their formula for additives and then puts it in trucks to ship to local stations. But, since the gas is all the same, and the additives all do essentially the same thing, where you get your gas from doesn't matter.
The particular station may matter because it could have bad tanks with water in them or dirt, but the actual gas they sell is pretty much the same regardless of where you go.
I've experimented with different stations and it doesn't seem to change anything. I haven't used additives yet. That is the next step i guess.
Drifting
Joined: Feb 2005
Posts: 2,248
Likes: 414
From: Coachella Valley
This is correct to the extent that all gasoline must meet minimum specs. Hence, it is considered fungible, ie, one gallon is the same as another. But it is also true that some fuel exceeds the specs. Octane is a good example because it is a min spec. That means that the 91 octane gasoline better not be 90 but it may be 92 or 93. And yes, refineries occasionally give away octane.
This is true with the exception that most refineries have dedicated lines to their regional terminals as opposed to using KinderMorgan's shared pipelines (which are designed for statewide distribution). If you live near a refinery and buy branded gasoline, you are most likely getting gasoline straight from their refinery.
The majors will argue until they're blue in the face that their additives are superior. And there's some truth to that. Hence, all gallons are not the same.
Dave (a Bay Area Chem E that has spent his share of time in a refinery)
All refineries, whether they are Valero or Shell owned, 91 octane or diesel, pump gas into a common pipeline that distributes that gas to distribution centers near where the gas will be delivered. Once Shell dumps gas into the pipeline, they can extract the same amount from the pipeline at their distribution centers. The gas takes some time to travel in the pipeline, so the gas that the Shell distribution center takes out, may not be from a Shell refinery. It could be from a Valero refinery. Because it is a common formula, it doesn't matter.
Dave (a Bay Area Chem E that has spent his share of time in a refinery)
