There is a degree of overlap in the hydrocarbons used for gasoline and diesel fuel, and refineries routinely adjust the ratio they produce to match seasonal var

There is a degree of overlap in the hydrocarbons used for gasoline and diesel fuel, and refineries routinely adjust the ratio they produce to match seasonal variation in demand. It's also possible to crack the heavier hydrocarbons in crude oil into molecules suitable for diesel, which is an important consideration as lighter crude oil supplies are being supplanted by heavier oils from tar sands and shale. In the longer term, there's also the possibility of refining less oil and supplementing with biodiesels.