New lower sulphur diesel will have a sulphur level of no more than 50 ppm (parts per million), down from today's 500 ppm. It will be introduced progressively from September 2005 and from 1 January 2006 lower sulphur diesel will be the only diesel available. The move to lower sulphur diesel is a result of changes under the Petroleum Products Specifications Regulations 2002, which define the legal standards for petrol and diesel.

Sulphur in diesel can increase the amount of very tiny particles (called particulates) that your vehicle emits. Particulates have been linked to health problems, in particular respiratory conditions. Lowering the sulphur levels in diesel can directly reduce particulate emissions from diesel vehicles.

Lower sulphur diesel will also facilitate the importation of the latest clean diesel vehicles featuring advanced emissions control technologies. These vehicles will further reduce particulate emissions as well as other harmful emissions such as nitrogen oxides, hydrocarbons and carbon monoxide.

Whilst the reduction in sulphur level is the most significant change being made to diesel, minimum cetane index (burning quality) is also being improved. Lubricity will continue to meet the current specifications for diesel.

Will This Affect My Diesel Vehicle?

Well maintained and newer diesel engines are unlikely to be affected by the new lower sulphur diesel fuel. Older or poorly maintained diesel engines may be affected. This is because the process used to lower sulphur levels in diesel may also lower levels of specific compounds - aromatics - in the fuel.

As diesel systems age they may leak for a variety of reasons and replacing injector pump seals is part of routine maintenance. In some older diesel engines, fuel injection pump seals may be affected by the levels of aromatics in the diesel - swelling when levels are increased and shrinking when levels decrease. The combination of seal shrinking resulting from seal ageing and low aromatics diesel could result in leaks in one or more of the fuel injector pump seals.

The main type of pumps that could be affected are older VE rotary fuel injector pumps made by Denso or Zexel that haven't been maintained for six or more years (but other pumps could also be affected). Generally these pumps can be found in pre-1995 Japanese light duty diesel vehicles.

A fuel injector pump seal leak is likely to result in poor engine fuel efficiency and a smoky exhaust, or a visible fuel leak. If a seal leak is neglected, more serious engine faults could develop.

What Should I Do?

Diesel engines should be regularly maintained. This is important for the safe, clean and efficient operation of diesel vehicles. Air cleaners, injectors, fuel pumps and pump seals should be checked and repaired or replaced by your diesel mechanic at the correct time intervals. Your owner's handbook will indicate how often each of these checks should be made.

Lower sulphur diesel will start being supplied from September 2005 onwards. From this time, particularly if you have an older diesel vehicle, you should regularly check for:

any diesel pooling under your vehicle,
moisture or wetness at the bottom of the engine,
changes in engine exhaust (e.g. a smoky exhaust),
any unusual smell of diesel when using your vehicle, or
decreases in the fuel efficiency of your vehicle.

If any of these things happen, you should get your fuel injection pump checked.

If you have a pre-1995 vehicle with a type VE fuel injector pump that has never been serviced, you may wish to consider a maintenance overhaul and seal replacement before lower sulphur diesel is introduced to avoid unplanned downtime.

Once you have had your injector pump serviced and the seals replaced, the new seals should last for six to eight years.

For More Information

Talk to your diesel mechanic or parts supplier
Call free 0508 33 55 33 [this number is no longer active]
Visit Lower Sulphur Diesel

This information has been prepared by the Ministry of Economic Development in consultation with BP, Caltex, Challenge, Mobil and Shell.

Technical advice was provided by the Motor Trade Association and the Association of Australasian Diesel Specialists.

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Printed: 25/11/2009

If You Drive a Diesel Vehicle You Need to Read This

Contents

What's Happening to Diesel and Why?

Will This Affect My Diesel Vehicle?

What Should I Do?

For More Information