The Highway Diesel Rule, finalized in 2001, was put in place to reduce emissions from diesel powered heavy-duty vehicles and equipment. The Environmental Protection Agency (EPA) set new strict federal emissions standards for heavy-duty diesel engines and the allowable sulphur content in diesel fuel. For on highway vehicles these standards required engine manufacturers to reduce emissions by 90 percent no later than engine model year 2007. In order to achieve lower emissions these new engines required implementation of technologies such as exhaust gas re-circulation (EGR) in addition to other new emissions control devices. As a result engines designed for compliance with the new emissions standards cannot tolerate high levels of sulphur in diesel fuel.

If you purchase a new vehicle with a 2007 emissions compliant engine the only fuel you can use in that vehicle is the Ultra Low Sulphur Diesel (ULSD). Aside from being subject to fines because it is against the law to use higher sulphur content fuel in new emissions compliant vehicles, improper fuel use will reduce the efficiency and durability of the new engines, permanently damage advanced emissions control systems, reduce fuel economy and possibly prevent the vehicle from running at all in addition to likely voiding the manufacturers warranty.

If you own a vehicle with a pre-07 engine you may use either the new ULSD fuel or the Low Sulphur Diesel (LSD) while still available. By the end of 2010 only ULSD fuel will be available for highway use so over the next couple of years it will likely become more difficult to find the LSD fuel at service stations. Keep in mind it is possible to have a 2007 model year vehicle built with a 2006 model year engine that is not equipped with sulphur-sensitive advanced emission control systems. These vehicles do not require ULSD fuel and EPA does not require that these vehicles be fuelled with ULSD fuel. If you are unsure about your vehicle’s fuel requirement contact your dealer or manufacturer.

Sulphur is a natural lubricating component in fuel. However, for the most part, sulphur can be considered an undesirable component in fuel due to its negative effects on our equipment, environment and health. For example during the combustion process sulphur forms sulphuric acid, which can be highly corrosive to internal engine and exhaust parts. Sulphur compounds that are expelled into the atmosphere with vehicle exhaust contribute to what is known as acid rain. Also when sulphur chemically combines with oxygen in the air it forms sulphates, which in turn are inhaled into our lungs contributing to certain illnesses.  Reducing the sulphur content in diesel fuel has many benefits.

1) Will the ULSD fuel create any operational problems?

New engines are equipped with emissions control devices and were specifically designed to run on the ULSD fuel. These new engines will likely run hotter but following the manufactures maintenance and operational guidelines will help eliminate problems with regard to fuel. Remember you must always check the pump labels to ensure you are refuelling with the proper diesel fuel for your vehicle. Representatives from the petroleum industry and manufacturers have stated during the transitioning period there may be some instances where the introduction of ULSD fuel to older vehicles may affect fuel system components or loosen deposits in fuel tanks. The hydro-treating processes used to reduce the sulphur content of diesel also remove other compounds including aromatics and naturally occurring antioxidants, which help prevent the fuel from forming gums and sludge. This could potentially cause fuel system leaks or premature fuel filter plugging during the changeover period. As a preventative measure you may want to consider using a fuel additive product, such as Bi-Tron's Fuel Conditioner, which can offer multiple benefits such as increased lubricity, increased MPG, inhibiting corrosion, removal of water in fuel, preventing gelling and removal of sludge. The cost of the additive can be looked at as an investment rather than expense. Take a look at how much more per mile it would cost to run your vehicle with an additive and then look at how much it will save you by increasing your mpg and reducing the likelihood of fuel clogging or accelerated engine wear.

2) Will the ULSD fuel increase the wear on certain vehicle components?

The undisputed effect of lower sulphur in diesel fuel means lower lubricity, which is the property that directly effects wear in the fuel injectors and fuel pump. Several years ago, when low-sulphur diesel (500 ppm) was first mandated, there were incidences of leaking fuel systems particularly around injection pumps. The cause was contributed not to the removal of sulphur itself but rather to the aromatic compounds removed as result of the desulphurization process. The aromatic compounds in high-sulfur diesel (5,000 ppm) cause rubber O-rings to swell. When the aromatics were removed, the O-rings shrank, leading to fuel leaks. For years many diesel engines have been equipped with O-rings that are not susceptible to this swelling and shrinkage. Don’t assume your pre-07 vehicle is in the clear, ask your mechanic or manufacturer about your seals and O-rings and most importantly pay close attention to these areas especially during the transition period of switching to the ULSD fuel. A good way to monitor engine wear is to regularly get an oil analysis. Before you start fuelling with ULSD have your engine oil analyzed, which checks the oil’s viscosity, presence of contaminants and wear metals. This is like a blood test for your engine that helps you determine the condition of your engine. Each time you have your oil changed get another analysis. This will establish a comparison of wear on your engine and help you catch trouble areas so that you can take preventative measures to protect your vehicle.

3) Will the ULSD fuel yield lower miles per gallon?

The hydro treating processes used to reduce the sulphur content of diesel can adversely affect other fuel properties. ULSD does have a lower fuel density, which translates into a slight lowering of the energy content and subsequently increase in fuel consumption. Although no one seems to know exactly how much of a reduction we will see in mpg, the consensus is between 1%-3% if any at all. Many factors affect your mpg including speed, tire size and condition, equipment design, idling and fuel quality. To increase your miles per gallon without spending any money simply lower your speed. If you invest in a product that increases your mpg even by only 1%, that will translate into substantial savings over time.

4) Will ULSD fuel cost more than the LSD fuel?

Due to the increase in cost of producing and distributing diesel fuel, it is estimated that ULSD will probably cost about five cents more per gallon than LSD. Likewise we will see an increase in cost for new diesel powered vehicles due to the increase in cost for the low emissions engine.

The transition to the new ULSD fuel reminds us that proper maintenance is vital to the life of your vehicle and learning how to achieve maximum miles per gallon is critical to reducing your costs. If you do not currently schedule routine maintenance at regular intervals, refer to your manufacturer’s manual and develop good maintenance plan.  While it is anticipated that ULSD should not interfere with the operation of older vehicles, to minimize the potential for issues it may be beneficial to make some adjustments to maintenance practices such as frequently checking filters, regular engine oil analysis, using fuel additives, not running your fuel tanks to near empty and consider cost effective solutions to improve your fuel miles per gallon.

By implementing new emission standards for heavy-duty engines and ULSD fuel standards, EPA regulations are expected to dramatically reduce the air pollution from heavy-duty vehicles. When fully implemented EPA estimates 2.6 million tons of smog-causing nitrogen oxide emissions will be reduced each year. Soot or particulate matter will be reduced by 110,000 tons a year. An estimated 8,300 premature deaths, 5,500 cases of chronic bronchitis and 17,600 cases of acute bronchitis in children will also be prevented annually. An estimated 360,000 asthma attacks and 386,000 cases of respiratory symptoms in asthmatic children will be avoided every year. 1.5 million lost workdays, 7,100 hospital visits and 2,400 emergency room visits for asthma will be prevented.


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