if you ever get caught could be really bad people have done prison time over running red dye offroad fuel and i have seen several people get nabbed for it as i come from farm country and the farm kids often run farm diesel and several got caught and it didnt go well for them.
upto 20yrs in prison / upto $10,000 in fines / 10yrs of probation ( another $5,000~ in cost ) / also you wear that issue for rest of your life every time you go thru any weigh station or are pulled over that is on your record and will push the officer to check and further search and hassle you ( it gives them a legal excuse to do so )
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once you get a felony its for life remember that add to it tax evasion will also be on your record for rest of your life this could seriously hurt you job wise again for rest of your life.