Did you try sprinkling kitty liter on it and leave it sit for a couple of days and sweep it up. If this doesn’t work i would try some lemon juice in water and wash it down with this. About one large bottle per half gallon.
i dont know for sure what you could use.the problem is the fuel oil has soaked into everything,i think you are going to have a heck of a time getting rid of that smell. i dont think you ever will. maybe if you got a wet/dry vac and just sloshed the floor down real good, let it soak for a bit and then extracted the soap on the floor. might help. you could then use baking soda. let it sit over night to soak up the rest. good luck!