fuel economy ???

Has anyone noticed a flucuation in fuel mileage when they use diesel fron different companies? Here in Central Texas, there are only a couple on kinds of diesel available. We have Diamond Shamrock (Valero)
and we have Shell (Texaco). I normally fill up at the Shamrock and run between 18-22 mpg in my 2000 CTD 4x4.
The other night the Shamrock was out of diesel so I had to go to the Shell across the street and fill up. For some reason, I've noticed that my temperature gauge is running about 200 instead of 190. I've also experienced a decline in fuel mileage. I've went down to 14-16 mpg.
I know the obvious answer would be -- don't go back to Shell. I was just wondering if there was different additives they use or different refining techniques. Does the added temperature help the decline in fuel mileage ? Why would one be better than the other ?
I love my CTD, but these things are hard to figure out !!
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<snip>

The distillation of crude in crude units are basically the same everywhere. Differences come about with different crudes that are on fringes of what we normally use. This part of the process is the same for Shell, Valero and all the others.
After the Diesel side cuts comes off the Atmospheric Column and the Vacuum Column in the Crude Unit, it goes off to the Diesel Hydrotreater to get cleaned up, treated further and sent off to storage. Additives are blended into the fuel prior to the trucks picking it up at the loading rack. (for those refiners that supply multiple brands, additives are blended to match the brand. Think of it as a paint supplier. They supply basic white paint and additives to blend into the end product "color" the customer wants.) It is this portion of the process (DHT and additives) that introduces the differences between the refiners.
Then you have the potential differences in condition of the underground tanks and lines at the stations and whatever contaminates might have entered the tanks.
So, yeah, fuel from different brands and different stations can be different. Personnally, I wouldn't put Shell into any of my vehicles. I didn't like their gasoline and don't like their diesel. YMMV
FMB
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up here in NE Texas most of the fuel comes out of el dorado, AR
talking to the fuel jockeys on the CB I found out that most of the fuel has been coming out of Louisiana for the last 2 weeks.
my mpg has dropped from 16-17 to 14-15 in the last 2 weeks. connection?
--
Billy
1995 Ram 2500 4x4 Cummins
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