IF they check your fuel (and they do, especially at farm shows) its a $10,000 fine. Probably up to a $10,000 fine but that can zap you for the full amount if they want. As for the staining, they would have to remove a fuel line or dop the fuel filter after your tank checked out O. K. A PITA job for alot of people. I kind of doubt that something could stain the fuel system. My opinion.
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'94 3500 4x4, 201,000 miles, Never had a cat, Auto w/shift kit (currently under remodification), 3. 54 Gears, TST #5 plate, 235-85-16s, Rancho 9000s w/remote, Isspro gauges inplace of cupholder & Amsoil Bumper to Bumper. NRA member.
"Warrantee? We don't need no stinking warrantee!"