A FOUR-month trial is to be carried out by the Royal Mail into the use of ultra-low sulphur diesel (ULSD) on its truck and van fleet. The aim of the trial is to enable the company to monitor the effects on engine performance and fuel consumption and to compare those obtained by using ordinary diesel as part of continuing efforts to become more environmentally friendly.

Mike Horlor, head of road transport strategy, said: 'With improvements being made at the refineries, there is now a real prospect of continuity of supply for this new fuel. Should we wish to make a complete switch to low sulphur diesel for the entire Royal Mail fleet, having the fuel in sufficient quantities is vital for a commercial operation.' But such a decision must come after a thorough evaluation of the fuel. There have been some concerns about its effects on engine lubrication as well as the possibility of damaging seals in the fuel system.

The trial, which will be carried out in Swansea, will also assess how the new diesel performs in the stop-start driving conditions common to Royal Mail vehicles. Laboratory emission tests commissioned by Royal Mail have shown a promising 25% reduction in airborne particles compared with ordinary diesel and a 4% reduction in carbon dioxide. The sulphur content of ULSD is at least 90% lower than standard diesel.