Sometimes when you are in the country for a rest stop or at a filling station, you might notice there is a special diesel pump next to the regular pumps. The label on it says that it is only for off-side use and it is red diesel that it pumps. But what is red diesel and how is it different from regular clear diesel?

Simply put, red diesel is regular diesel dyed red. The only difference between two is that there is no fuel tax for red diesel.

In the US tax fuel is always included in the price so most of us don’t even think about it. The tax money pay for road work and basically this is the way you pay for using public roads. The tax rate varies from state to state, and that is the reason fuel costs are higher in some states than in others.

Red diesel is used off-road for farm equipment, train engines, generators, etc. In some states municipal and government vehicles can use red diesel at public roads, but private and commercial buyers are only allowed to use it on private property. If you use it for your truck or other vehicle on a road, it is like using roads for free.

Red diesel and clear diesel used to be different. Types of diesel differ by the sulfur content. Removing sulfur is expensive and takes a lot of time. Prior the beginning of the 90s, diesel with higher sulfur content was sold for commercial use. During the following decade the US was moving towards cleaner diesel to protect the air from pollution.

Today it is required that all diesel fuel, including red, is required to have ultra-low sulfur content. It means that there is no more difference between regular diesel and red diesel except for the latter dyed red.

So if at some point you decide to save on fuel, there will be no damage to your truck engine when you use red diesel. The only damage you will face is financial once you are caught “running red”. Legally, running on red diesel on public roads is tax evasion. For the first time they catch you with red diesel, you will end up with a fine of $1000 or more. The second and third time can go up to $5000 and $10000. DOT inspection can check your fuel any time your truck is under their inspection. And the worst part is that even when you run on clean fuel after using red, the red stains will still be visible in your fuel system for the inspectors to see.

If you use off-road equipment, it is fully legal for you to use red diesel. The problem is the red diesel is not always easy to find, and if you don’t, you can claim a tax write-off to be paid back.