linger in a truck’s fuel system

https://southdakotasearchlight.com/wp-content/uploads/2026/10/100626-Red-Dyed-Diesel-web.mp3

Listen to an audio version of this story produced by reporter Meghan O’Brien. Broadcasters: See below for a downloadable version with a host intro script.

President Donald Trump is allowing broader use of a federally tax-exempt fuel that powers farm equipment, in an attempt to ease the burden of rising diesel prices. But some farmers are hesitant to accept the help.

The fuel is red-dyed diesel, which is legally limited to use in offroad machinery. The action by Trump has temporarily opened the fuel’s use to highway vehicles such as pickups and semitrucks.

Some farmers are worried about expanding their use of red-dyed diesel, saying the dye could linger in fuel tanks and expose them to potential future fines.

“Once this expires, and there’s still red-dye diesel in the trucks going down the road, how will the enforcement be handled then?” said Scott VanderWal, president of the South Dakota Farm Bureau. “Because it takes a long time for that to work through, and there still would be traces of the dyed diesel in a truck as much as a year or so later.”

After Trump’s Monday announcement, Republican Gov. Larry Rhoden issued a corresponding directive Tuesday allowing broader dyed-diesel use in South Dakota. Josie Harms, a spokesperson for Rhoden, responded to South Dakota Searchlight questions about lingering dye in fuel tanks.

“While residue can be detected for longer, a simple color check can determine if the violation was recent or residual,” Harms said in a written statement.

Dyed diesel fuel is the same as standard diesel, except that it’s exempt from the federal 24.4 cent per-gallon diesel tax and dyed red. The dye allows enforcement officials to determine whether a driver is skirting the federal gas tax.

Some farmers buy dyed diesel from bulk providers who deliver it to farms. Dyed diesel is not widely available at gas stations, and dyed diesel used for agricultural purposes is exempt from state tax in South Dakota.

Using dyed diesel on public roads is illegal, but Trump announced an executive order Monday that nixes penalties through the end of the year. Following suit, Rhoden issued a directive Tuesday to the state Department of Public Safety to “prioritize commercial motor vehicle inspections that present a threat to public safety and not attempt to identify the use of dyed diesel fuel on highways and public roads” while the federal order is in effect.

South Dakota’s statewide average price for diesel fuel Tuesday was $5.98. Without the federal tax, a 250-gallon semitruck tank would be $60 cheaper to fill.

“That’ll reduce the cost a little bit for getting our products either to the farms or to the market, from the fields,” said VanderWal. “It’s not a huge help, but every little thing helps.”

State Department of Transportation officials check fuel tanks with a stick that, when removed from the tank, shows if the fuel contains red dye. Semitruck tanks can be checked at weigh stations, and Baltic-area farmer Ron Krogstad said officers also check parked vehicles.

“They check salebarns, they check diesel pickups,” Krogstad said. “I mean, they’ll go places where the farmers go for coffee, and I guess they have the right to check your diesel fuel tank if they so choose.”

Reid Jensen, a farmer from rural Burbank, shares VanderWal’s concern about future enforcement.

“Nobody’s telling us that yet,” Jensen said. “The details haven’t been worked out.”

Violations can be punished by fines, civil penalties and prosecution for failure to pay, so taking a chance and driving on public roads with dyed diesel has traditionally been considered “just not worth it,” said South Dakota Farmers Union President Doug Sombke. Because enforcement can happen when a vehicle is parked, he said, officers could check a tank and “you wouldn’t even know they did it.”

Sombke said attempting to help farmers by allowing them to temporarily use more dyed diesel does not get to the root of high fuel costs, such as the negative effect on global fuel supplies caused by Trump’s war in Iran.

“We’re going to save a few cents per gallon,” Sombke said. “It’s a Band-Aid on a bleeding artery, is what it is.”

Last week, in another move intended to ease the burden of high diesel prices, Rhoden issued an executive order allowing farmers to haul agricultural products such as crops and livestock at 10% above weight restrictions and without a $25 overweight permit.

This story was originally produced by South Dakota Searchlight, which is part of States Newsroom, a nonprofit news network which includes North Dakota Monitor, and is supported by grants and a coalition of donors as a 501c(3) public charity.