Ultra-Low Sulfur Delivers Better Air Quality

Recently, diesel fuel standards have changed. The fuel currently being used is most likely the new EPA-Mandated Ultra-Low Sulfur Diesel Fuel (ULSD), which contains less than 15 parts per million (ppm) sulfur. ULSD will replace all low-sulfur diesel in the USA by 2010 except for California which already meets the ULSD standard. While ULSD delivers significant benefits to the environment, it does not protect and lubricate as well as the old fuel. As a result, fleet operators and diesel truck owners may need to replace the lost lubricity with fuel additives to help preserve engine life and maintain performance.


Some premium diesel fuels already contain the lubricity additives. For diesel fuel without the additives, the Solder Seal® Gunk® Diesel brand of “diesel sulfur-substitute” replaces the natural lubricating properties of sulfur without the environmental issues. Lubricity of sulfur-substitutes protect vital engine and fuel-line parts, helps maintain engine design life, and helps save money on costly repairs.

EPA–mandated ultra-low sulfur diesel fuel will
replace all low-sulfur diesel by 2010.

What was behind the change in diesel fuel standards?

EPA–mandated ultra-low sulfur diesel fuel will replace all low-sulfur diesel by 2010. ULSD fuel meets significantly lowered sulfur levels of 15 parts per million (ppm) of sulfur compared to earlier low sulfur diesel fuel of about 500 ppm. The new diesel levels were established and adopted in Canada, Europe and now the US. US diesel engine technology was modified for the 2007 model year to deliver adequate performance while lowering particulate emissions when using the new ULSD fuel, which will lower emissions in pre-2007 model year diesel engines as well. However, some 2007 model year vehicles are equipped with earlier engines which do not require ULSD.

Environmental benefits from ULSD

ULSD fuel enables the use of cleaner technology diesel engines and vehicles, resulting in significantly improved air quality. The annual emission reductions from using ULSD will be equivalent to removing the pollution from more than 90 percent of today’s trucks and buses, when the current heavy-duty vehicle fleet has been completely replaced in 2030. EPA tests by the California Air Resources Board (CARB), engine manufacturers and independent organizations, show that use of ULSD in vehicles with the latest emissions control systems, reduces emissions of hydrocarbons, oxides, nitrogen, and particulates to near-zero levels. Studies by the EPA concluded that ozone and particulate matter cause a range of health problems, including those related to breathing, putting children and the elderly at risk. EPA estimates that there are significant health benefits associated with this new fuel. Use of ULSD fuel in diesel-powered passenger cars and light trucks will allow diesel vehicles to meet the same stringent emissions standards as gasoline vehicles.

US regulations require labeling

By law, labels must be used on diesel fuel pumps, vehicle fuel tanks, and fuel gauges identifying that the fuel is ULSD. Fleets and consumers should check the pump and vehicle labels to be sure that they are operating the vehicle with appropriate fuel. Additives must be properly labeled.

ULSD Engines use a new Engine Oil Grade ULSD contains less sulfur and that translates into less lubrication and more potential wear and tear. Manufacturers have developed a new formulation for diesel engine oils that is suited to the task. API CJ-4 oils are also engineered for use in previous model year engines and intended to maintain oil drain intervals when used in conjunction with ULSD. Of course, fleets and consumers should follow engine manufacturers' recommended guidelines.

Winterize Your Fuel Makers and distributors of ULSD fuel may or may not winterize fuel. It is necessary to reduce the viscosity of winter fuel by blending only Ultra Low Sulfur Kerosene (ULSK) or use high grade additives. ULSK is effectively the “No.1 Diesel Fuel” that also contains less than 15 ppm of sulfur. ULSK may be blended with ULSD and does not downgrade the fuel performance. Like ULSD, ULSK may not be available in all areas or truck stops. GUNK Anti-Gel and De-Gel additives are designed to cope with cold weather effects on fuel. GUNK Brake Line Anti-Freeze #1MRA2 also helps protect brake lines from freezing.

Cold climate diesels may experience some issues

Issues may develop with fuel icing and gelling in the cold weather. When ULSD fuel temperatures reach 0 to –15 degrees F, good fuel additives should provide adequate protection. Below -15F (sometimes called the “cold filter plug point”), ULSD thickens and will not flow through a fuel filter. ULSD must be treated with fuel additives and/or ULSK kerosene to keep fuel flowing.

Prior to the introduction of ULSD, a cold filter plug point of -15 to -30F was not a problem. Many fuel retail stations and truck stops do not pre-treat their diesel fuel for winter use. Therefore, high quality fuel additives and ULSK should be used on a regular basis to prevent icing and gelling for trouble-free operation. The additives and kerosene should be added BEFORE fuel starvation/stalling symptoms occur. Once the fuel reaches the waxing/gelling point, additives will not properly mix with the fuel and will not free-up the fuel filter until it warms up.

Diesel additives contain needed agents

These help lubricate fuel pumps, resist corrosion, improve the life of equipment, improve acceleration and power, limit filter plugging, enable good low temperature operation, maintain a clean fuel system, disperse water in fuel systems, condition fuel, and help keep engines operating like new, longer. ULSD used with a Sulfur Substitute & Conditioner (1MRB3) replaces lubricity lost in low-sulfur fuels, improves performance, decreases emissions, extends fuel filter life, keeps injectors clean, improves acceleration, disperses water in fuel systems, and is safe for all diesels.

Fleet and vehicle maintenance issues

ULSD fuel is fully compatible with older technology diesel engines prior to 2006, but in some cases, use of ULSD fuel in 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 should monitor their diesel-powered vehicles closely for potential fuel system leaks, premature fuel filter plugging, and winterizing fuel treatment.

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