So...I have been under the impression for some time that the BTU content of these blends are the same. However, on the occasions that I have filled with #1 diesel in warm weather, it seems that my average MPG on the DIC begins to climb.

Yesterday I drove unloaded about 180 miles, filled and realized I put in #1 diesel. On the way home, same speed, I added about 1mpg to my average.

Coincidence? Factual? Maybe a tailwind on the way home, instead of a headwind?