@rplst8 posted:This is incorrect. The overwhelming majority of home heating fuel in the US is #2 fuel oil. Additionally, #1 fuel oil is sold as Kerosene and sometimes jet fuel.
Road diesel is a sub-class of #2 fuel oil that specifies a cetane number (which basically indicates ignition temperature) and then for sulfur content. Generally any #2 fuel oil (and sometimes #1) that is not subject to transportation excise taxes is dyed to prevent use in on-road motor vehicles. If you're suspected of using untaxed fuel, a simple inspection of the fuel filter will determine if a violation occurred.
A typical diesel engine can run on pretty much any of these fuels (and maybe more) because they are built so robustly, they don't need ACTUAL diesel fuel. Long term you can cause damage (especially using #1) but also with some of the #2 fuels when they are used in newer vehicles. The reasons for this are varied, but usually with #1 it's because it doesn't lubricate the injectors well enough. With #2, the newer diesel engines expect ultra low sulfur diesel, but I don't know if it's more a problem for the engine itself, or the emissions equipment.
Low sulfur diesel is because of emissions regulations as far as I know, they limit the sulfate emissions that cause acid rain. You are right about dye being used on untaxed products.
Kerosene is #1 fuel oil. Kerosene can cause problems in diesel engines because it burns a lot hotter, and that can cause damage. On the other hand, it was common to mix kerosene with #2 diesel fuel, among other things helps prevent waxing in cold weather.
Note, you wouldn't want to use #1 fuel oil (kerosene) in a oil fired furnace unless it is designed to use it. #1 burns a lot hotter and could cause severe damage if used in a typical home oil fired furnace or boiler. #2 diesel fuel and #2 heating oil are similar, but besides road use taxes, #2 diesel fuel has additives to it for cold weather operation and the like that heating oil doesn't have.
