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LOW SULFUR DIESEL

Cleaner Diesel

All Australians now have access to a cleaner, low sulfur diesel.

Under the National Fuel Standards, introduced by the Commonwealth Government at the start of 2002, a mandatory proram has been established for progressive introduction of cleaner diesel and petrol. These new fuels will reduce pollution from all engines and enable the introduction of new engine technologies that will provide improved fuel efficiency and further reduce tailpipe emissions.

One of the key elements of this program is a major reduction in the level of sulfur present in diesel fuel.
From 31 December 2002, it is mandatory for all diesel sold in Australia to contain less than 500 parts per million (ppm) sulfur, typically referred to as Low Sulfur Diesel. This compares to previous typical production with around double that level.

Low Sulfur Diesel has been mandated in Western Australia and Queensland since 2000. It is now the standard diesel for all States.

This important advance brings Australia closer to Europe and the USA in diesel fuel quality

Timing

From 31 December 2002, it is mandatory that all diesel sold in Australia meets the low sulfur specification of under 500ppm. To ensure compliance with this regulation, fuel suppliers have been introducing the new diesel in advance of that date.

Diesel vehicle operators should therefore expect Low Sulfur Diesel to have been introduced into the market by the end of 2002, except for the two States in which it is already standard.

Impacts of Low Sulfur Diesel

Diesel users should not experience any differences in vehicle performance on Low Sulfur Diesel.

However, users need to be aware of two potential issues.

Lubricity

Refinery processing of diesel to reduce the sulfur level can have the undesired effect of reducing the natural lubricating properties of the diesel, which are essential for the good operation of fuel system components such as fuel pumps and injectors.

A diesel lubricity specification has been introduced as part of the mandatory national fuel standards, which all diesel must meet.

Impact on Seals in Fuel Pumps

The production of Low Sulfur Diesel leads to changes in the composition and chemical properties of the fuel, other than sulfur content. In general, these changes are expected to be minor. However, there may be certain changes that could affect engine fuel systems. It is prudent to be aware of the possible effects on engines of such changes and take preventative maintenance action.

Some types of engine seals and O rings can react to changes in fuel composition by swelling or shrinking.

In current generation engines, and engines supplied generally post 1994, fuel system seals and O rings are made of FKM (also known as Viton), which is not affected by this process.

Fuel systems more than 8 years old may have seals made of nitrile rubber (also known as NBR or buna-n), which is not as resistant to changes in fuel composition as Viton.

When fuels of different composition are used, old seals made of nitrile rubber may not be able to adjust properly, and this may exacerbate the cracks or stresses already present due to the natural aging of the rubber. If this occurs, the solution is to replace the seals with new ones; after this, the problem should not reoccur.

As a consequence, it is recommended that owners of older vehicles with older nitrile rubber fuel system seals consider changing any such suspect seals at the next maintenance.

Low sulfur diesel is an important step in the program to introduce new engine technology and fuels that will benefit both vehicle users and the broader community.

For further information, contact the vehicle manufacturer, your fuel supplier, your State motoring association, or reputable provider of service/maintenance for your particular vehicle.