People can only cut heating oil usage so much, and then they are not heating. Diesel fuel comes from the same fraction of the barrel of crude as fuel oil, and demand for diesel is not as elastic as the demand for gasoline. Although a lot of private vehicles use diesel, the major applications remain commercial, and primarily for long haul freight and passenger transportation, agriculture, trains, and even oil rigs. That demand remains more constant than, say gasoline, which comes from a different fraction of crude oil, and primarily powers private passenger vehicles and light trucks.
Home heating oil demand is increasing with winter. It is a one-two punch, price wise (notice the price of diesel is staying up, also).
When the price of gas went up, people found a way to cut back on how much they used, hence the elasticity of demand is greater. As a result, the short supply of gasoline and the price spike have been shorter in duration than that for diesel and heating oil.
Joe, you are talking in circles, kind of like the evolutionist, let me just thank you for your help and let it drop there.