I worked in a refinery for 26 years but not in production....but the largest in the nation and the way it was explained is that most refiners do not have enough capacity to produce as much diesel vs gasoline and since gasoline is used by more, they concentrate production more to gas. And even though jet fuel is very similar to diesel, it's refined and filtered more than diesel is and thus has less lubricity than diesel and that in itself will wear injector pumps much faster. Removing more sulfur from diesel fuel was bad enough. The argument goes both ways about sulfur acting as a lubricant. Well, the winning argument is that when you refine more to remove more sulfur, you will also remove more lubricant oil from the product. Wholesalers? downstream are (were?) supposed to add a lubricant at time of delivery....but I'm sure all of them will jump right on that.I think that a big part of the reason diesel is more expensive than gasoline is because it's more chemically similar to jet fuel. It's all about demand. I'm not a refinery guy so I don't know the specifics but the way I understand it is that you can adjust the refining process a little to get more diesel/gasoline/jet fuel or whatever, but only by a certain amount. If there's more demand for one product vs another it will cause the market price to adjust accordingly. Maybe there's a refinery worker on the board than can enlighten me further???