During the last recession I owned and operated a gravel truck work was scarce and fuel even more difficult to purchase with out money.
People had switched from oil heating to gas, most of the tanks were left in place if you got lucky you could get one to haul away that had plenty of fuel left inside. Furnace oil and diesel are close enough in chemical nature to burn as fuel in a diesel engine.
I rigged up a small pump run from a gas engine to transfer the fuel, just make sure you filter it before putting it into a truck.
Even to day it's not by chance all my vehicles are diesel powered, the only difference is that I'm burning bio fuel made from waste restaurant oils.
Unfortunately hauling scrap uses more fuel than I'm able to make and I'm buying at the pump.