Clear Diesel & Dyed Diesel
No, performance is essentially the same. The only difference is the dye (and tax treatment). No. Using dyed diesel in a vehicle that travels on public roads is generally illegal and subject to fines. Technically, yes—they will still function. Penalties can include hefty fines (often thousands of dollars or more), being required to pay back taxes, and regulatory enforcement actions. Clear diesel is the standard “on-road” diesel fuel (also undyed) sold at pumps and used in vehicles traveling on public roads. Dyed diesel is chemically equivalent to clear diesel, but includes a red dye (often Solvent Red 26 or 164) as a marker. Because it is not taxed (or taxed less) like on-road (clear) diesel, dyed diesel can be significantly less expensive per gallon.
In some cases, dyed diesel may have slightly different sulfur content depending on region, but functionally they operate the same in diesel engines.
Regulators can detect even small amounts of the red dye during inspections.
However, mixing can complicate regulatory compliance (if the blend ends up in on-road equipment) and ensure you’re not unintentionally violating rules.
Under federal rules, each violation can incur a penalty of $1,000 or $10 per gallon of dyed diesel used improperly, whichever is greater.
It is subject to federal and state fuel taxes.
That dye indicates the fuel is intended for off-road (non-highway) use—like on construction equipment, generators, agricultural machinery, etc.
Dyed diesel is typically exempt (or partially exempt) from highway fuel taxes.