Low Sulphur Diesel

From 31st December 2002, it was mandatory that all Diesel sold in Australia met the low sulphur specification of under 500ppm.  The production of Low Sulphur Diesel leads to changes in the composition and chemical properties of the fuel other than sulphur content.

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 Viton, which is not effected by this process.

Fuel systems more than 8 years old may have seals made of nitrile rubber which is not as resistant to changes in fuel composition as Viton.  These old seals may not be able to adjust properly, and this may exacerbate the cracks and stresses already present due to natural aging requiring their replacement.

To date there have been no reports of Waste Vegetable Oil as fuel effecting the nitrile rubber in this manner, although some natural rubbers may be effected by Biodiesel.