Wow, what a lot of misinformation abounds about clear and red diesel. A few facts: Off-road red diesel has NOT gone through the extreme "hydro-cracking" process which removes the excess sulfur. This refining process actually LOWERS the lubricity of the diesel -- it is the process; not the low sulfur, which "harms" the diesel. Sulfur is NOT a lubricant; but clear low-sulfur diesel has less lubricity due to the extreme refining process. FACT: Clean fresh red diesel is actually "better" for your fuel system than the low-sulfur stuff due to the otherwise similar cetane & chemical characteristics, plus the higher lubricity... not that I even REMOTELY recommend it; it is highly illegal and getting caught will result in stiff fines. Sulfur compounds result in higher nitrous oxides in the exhaust; not excessive particulates. The slight amount of sulfur in clean fresh red diesel could take over 100K miles to contaminate the catalytic converter under normal operating conditions. And there is no sensor on any on-highway vehicle (that I am aware of) to "detect" the presence of red diesel... although I'm quite sure that there are numeous state troopers who have the equipment to detect it in your tank. I am not a petroleum engineer; I am a service manager at a farm equipment/tractor dealership. These facts are readily available in trade magazines like DIESEL PROGRESS and on the internet.