My brother just called. His furnace stopped working and he's pretty sure he's out of fuel. He called the oil company but it would cost $400 for them to just come out today. I've looked online and found that, in a pinch, you can use automotive diesel fuel in your home heating oil furnace. Is this true? Has anyone done it? The hope is that the delivery charge won't be so steep if he can limp along on diesel for the night and get them to come out during the week vs the weekend.