Just for all the upstanding law abiding karma police, burning wvo or homemade biodiesel is every bit the same law breaking as using hho.
You didn't pay the tax, you can't use it on the street.
As for hho being different than #2 diesel, kid yourself all you want that the refinery is producing two extremely similar yet different fuels.
I have been to about 50 different forums that discuss this very issue, and the most reliable info has it that they are the same.
In fact, read the MSDS. The refinery defines #2 fuel oil as Diesel and Home Heating Oil. They even get sent in the same pipeline.

Legally speaking, using hho is illegal (not really sure if it is a LAW, or a TAX CODE which is being broken), but is it unethical?
I think that as long as diesel costs more than gasoline, then using untaxed hho is leveling an unfair playing field. It doesn't cost more to produce diesel, it costs more for gasoline, so where is the extra money going?
Maybe right to the politicians who allow the oil companies to rape the consumer? What is the current level of tax per gallon on diesel? At one point I paid $2.25 for hho and diesel at the pump was at $4.10. Are there REALLY $1.85 in taxes being levied, if not why the extra cost? According to the Energy Information Administration http://www.eia.doe.gov
the federal taxes in 08 were 24.4 cents/gallon and state taxes averaged about 22 cents/gallon.
Follow the money!!!

They quit rippin me off, I'll start folowing the rules!!!!

Then the penalties. I've never heard of DOT dipping the tank on a passenger vehicle. I don't think they even could, short of siphoning fuel out of the tank. Be kinda hard to get that stick through the fill tube.