It's a way to save nineteen cents per gallon on diesel fuel, but it's against the law.
The state tax department is teaming up with the Highway Patrol to conduct fuel compliance checks.
The problem is the misuse of dyed diesel fuel. The agencies are checking gas tanks across the state.
Dyed diesel is used for things considered "off road" such as agriculture. Dyed fuel is taxed at four-cents per gallon.
Clear diesel fuel is taxed at twenty-three cents per gallon. It's used over the road for things such as transportation.
The tax dollars collected help pay for road improvements.
Over three thousand vehicles were tested. Fifty three were found to be illegally using dyed fuel.
"That's only less than two percent so we think that's pretty good. But we were very interested to find out that the violations out west were not as significant as some in the eastern part of the state," says Tax Commissioner Cory Fong.
Checks started statewide a year ago and will continue.
Fong says dyed diesel is available at stations in the state but is clearly marked.
Fines range from 250 dollars to five thousand.