Huh, just checked gas buddy and the spread on diesel between stations is $1.50 vs the spread on regular gas at $0.50. At the station with the best price on diesel it's $4.49 vs $3.39 for regular.
As far as heating oil is concerned, in 2020 residential use was about 3B gallons, about 1/4th of what it was in the late 70s and a much smaller percentage of the total distillate useage, though it's still a concern in the NE and NY in particular as refineries have to tune for it during the leadup and during the winter months.