Ultra Low Sulfur Diesel is compatible with existing fleets
with comparable performance.

Owners of 2007 and later model year diesel-powered highway vehicles must refuel only with ULSD fuel.* Owners of 2006 and earlier model year diesel-powered highway engines and vehicles may use ULSD or Low Sulfur Diesel fuel during the transition period. Only ULSD fuel will be available for highway use starting on December 1, 2010.

Under typical operating conditions, there should be no noticeable impact on overall power using ULSD fuel. Fuel economy may be reduced slightly because the process that removes sulfur also can reduce the energy content of the fuel.

ULSD fuel is fully compatible with the existing fleet, including 2006 and earlier model year vehicles. In some instances, the introduction of ULSD fuel to older vehicles may affect fuel system components or loosen deposits in fuel tanks. As part of a good maintenance program, owners and operators of existing cars, trucks and buses are encouraged to monitor their diesel-powered vehicles closely for potential fuel system leaks or premature fuel filter plugging during the change-over to ULSD fuel.

New engine oils have been developed for high-performance diesel engines designed to meet 2007 on-highway exhaust emission standards for use in conjunction with Ultra Low Sulfur Diesel fuel.  

Like Low Sulfur Diesel fuel, ULSD fuel requires good lubricity and corrosion inhibitors to prevent unacceptable engine wear. As necessary, additives to increase lubricity and to inhibit corrosion are added to ULSD fuel prior to its retail sale. With these additives, ULSD fuel performs as well as Low Sulfur Diesel fuel.

Diesel-powered highway engines and vehicles for 2007 and later model years are designed to operate only with ULSD fuel. Improper fuel use will reduce the efficiency and durability of engines, permanently damage many advanced emissions control systems, reduce fuel economy, and possibly prevent the vehicles from running at all.* Manufacturer warranties are likely to be voided by improper fuel use. Additionally, burning Low Sulfur Diesel fuel (instead of ULSD fuel) in 2007 and later model year diesel cars, trucks and buses is illegal and punishable with civil penalties.*

For regulated parties in the fuel distribution chain (including retailers and fleet operators), only Ultra Low Sulfur Kerosene (No. 1 diesel with no more than 15 ppm sulfur) may be blended with ULSD without downgrading the fuel.
EPA Winterization Standards Letter 11-30-07
Individual vehicle owners may add Low Sulfur (up to 500 ppm sulfur) No. 1 Diesel to their vehicle’s fuel tank(s) as long as the vehicle does not require ULSD fuel.  Regardless of sulfur levels, the blend ratios will remain the same.  Like ULSD, Ultra Low Sulfur Kerosene may not be available in all areas

Most engine and vehicle manufacturers allow biodiesel blends in concentrations up to five percent provided the biodiesel meets accepted (ASTM) fuel quality standards. (Biodiesel blends are mixtures of petroleum-based diesel fuels and fuels produced from soybean oil, waste cooking grease, or other organic matter. These fuels may contain biodiesel in concentrations ranging from two percent to levels approaching 100 percent by volume.) To ensure proper quality, consumers should use only biodiesel-ULSD fuel blends that are properly mixed by a qualified biodiesel blender. Consumers should not create their own biodiesel blends by adding biodiesel to ULSD fuel in a vehicle’s fuel tank.

There should be no operational problem if consumers switch from a biodiesel-ULSD fuel blend to ULSD fuel without biodiesel.

*Exception – Some 2007 model year medium-duty and heavy-duty trucks may be equipped with 2006 engines and emission systems. These vehicles are not required to use ULSD fuel.