quote:
Regarding brand name gas (Exxon, Chevron etc with proprietary additives), are they transported through a major distribution pipeline such as Colonial?

Yep.

quote:
If so, how are they kept separate from generic no-name gas?

They aren’t kept separate.

For most of the country, seeing a “Chevron” or “Shell” sign at a gas station does not mean that the gas being sold came from a Chevron or Shell refinery. The refineries mostly produce blendstock, not finished gasoline. That blendstock goes to a barge, pipeline, etc. and is carried to a blending facility/terminal near the end user. At this point it’s a generic commodity - not a finished, branded product.

Once at the terminal, the blendstock is further - erm - blended with ethanol, additives, and potentially other blendstocks to produce finished gasoline. This is where the gasoline becomes “branded” based on the particular Shell/Exxon/BP/etc. additive packages.

The exception is at fuel stations that are particularly close to refineries. If you buy gasoline at an Exxon station in Baton Rouge, there’s a decent chance it was blended at Exxon’s terminal. But even then it’s not a guarantee and depends (partly) on what agreements that specific refinery has in place with third party blenders/distributors.

Basically you can think about the large integrated oil companies as having three distinct businesses, which don’t necessarily interact much: upstream (oil & gas production), downstream (refining), and retail (finished gasoline, additives, and licensing). The same can be said for any other business units - for example, the raw components of Castrol lubricants don’t necessarily come from a BP refinery even though Castrol is part of BP.