In a Ford Truck Form Site, this is what was discussed;
Here is my $.02. there are only a few pipe lines in the country. EVery company shares these few pipelines to move their fuel from one part of the country to the other. it all gets mixed together. I am sure they keep gas, diesel and kerosene separate but Exxon's diesel is mixed with texaco's diesel. I heard of this on the history channel a couple months ago i wish i had paid more attention. Maybe someone else saw it and can add onto what i have said.
So, it appears that all diesel comes from the same pipeline...BUT!

From what I remember hearing, the oil companies dump a certain number of gallons of fuel in at one end, and then they're free to tap that much out at the other end. It's at that point that additives are added to make Texaco, Flying J, etc., have their own characteristics. What alanscott said about Flying J and their additives makes sense. I recently took a trip that took me in the opposite direction from my favorite Flying J, and I filled one of my tanks at a Shell truck stop along the way. I ran on that fuel first during the trip, and noticed how weak the truck seemed, and how lousy the mpg was. Once I remembered that I was running the Shell fuel, I switched tanks, and within a few miles, the truck was her old self again. Another wrinkle to this puzzle, is some Flying J's are company owned, like the one where I like the fuel, and some are not. There's one of those on the way to the truck stop with the good fuel, and the fuel isn't the same, and is about $.06 more per gallon.

This is exactly what I've been saying about diesel fuel and performance relative to mpg and lower regens....
I'm taking a trip at the end of March and will try Flying J...

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7.5 3500QC 6.7CTD 68RFE Build date June 2007
Superchips tuner 3808, Boost/EGT Laser Gauge, Airaid cold intake