Clear fuel is standard tax-paid diesel and gasoline, with no dye added. It is the fuel sold for highway use, and it is the opposite of dyed off-road fuel.
Highway fuel carries a per-gallon road tax, the tax that helps pay for roads. Fuel that has had that tax paid is left its natural color, with nothing added, which is why it is called clear. It is what goes into cars and highway trucks at any normal pump.
The contrast is dyed fuel. Off-road diesel is colored red to show the road tax was never paid on it, so it is legal only for uses that stay off public roads, like farm tractors, generators, and furnaces. Clear fuel is the taxed, on-road counterpart.
The plain word clear simply tells an inspector or a buyer that this is the taxed product. Red in the tank of a highway truck means trouble. Clear means the road tax is accounted for and the fuel is good to drive on.
For a jobber, clear and dyed diesel come from the same supply but are tracked and billed separately, because they carry different taxes. Keeping the two straight on every load is part of getting the tax right.
In useThe jobber drops clear, taxed diesel into the trucking fleet’s tank for its highway rigs, and red dyed diesel into the farm tank next door for the tractors.
See also Dyed diesel, Motor fuel excise tax, Marine fuel