To add to some RV'ers etc confusion, Meijer stores fuel stations (200+) in the Midwest only sells Premimum Diesel at it's pumps and it's the same price as the others in a given area. Where we live, Meijer fuel comes from the Marathon tank farm. At Meijer, it's labled the #1 grade of auto/RV Diesel and it's really #2 from the refinery but is micro fine filtered to further remove even the very fine impurity particles found in seasonally adjusted refinery grade #2. Then an injector cleaner and a lubricity agent is added. They claim up to 5% higher MPG's and we know it's does get better MPG's as we only use it when we are where it's available and if not have to use other brands. Our log book clearly shows a difference of 3%-4% between Meijer diesel and other brands over more than 150K of travel with our diesel all over the USA and Canada.
Florida and Washington State (the northwest) fuel consistently gives us the lowest MPG's and I suspect it's the constant higher humidity and humidity and hotter (expanded) fuel when pumped from the ground in Florida. Colder diesel is more dense per measure and usually holds less moisture just like you'd find in air temp differences. Warm light humid air rising creates the clouds in the cooler air and when at the saturation point, it rains!
Easy to understand with an engineering and/or physics/chemistry etc in your education background. Some people will even research it for themselves.
Some areas of North America are constantly very wet and others are very dry. Diesel fueled engines don't like water at all, not even a tiny amount and that's why they have water separator filters!