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 !!