Even the tiniest impurities in fuel could block minute holes in the injection nozzles of modern diesel engines.
The holes in the injectors can be as small as 0.001mm, meaning it is very easy for the holes to become clogged, engine experts warn.
Although misfuelling can cause the greatest damage to modern diesel engines, using low quality diesel can also cause problems.
Steve Smith, managing director of Feather Diesel Services, told members of the North East and Tyne Tees region of the Association of Car Fleet Operators: ‘Debris in fuel will clog such very small holes. That is why the correct fuels should be used and oil filters changed on a very regular basis. We carry out some changes at as little as 4,500 miles.
‘The filter is probably the cheapest thing that you fit to a car, but it is worth investing in high quality filters, because the tiniest impurities can damage the engine. Use a good-quality fuel, because you get what you pay for, and always use genuine parts.’
However, the problem with poor quality diesel is tiny compared to the rocketing problem of drivers mistakenly putting petrol in their diesel cars.
Smith said: ‘Modern diesels are so good that people can’t tell them from petrol engines.
“You must not move the car, but many drivers don’t know that in some cars, when you unlock the door, it activates the fuel pump to prepare the engine for starting.
‘This draws fuel through the whole system and causes damage without even starting the engine.’
ACFO regional secretary Vic Barnes said: ‘For fleets running large numbers of cars and vans this is certainly food for thought.’
The issue of fuel management is a prevalent one as the Government is considering its response to a court decision that it must comply with the European Union Sixth Directive, which blocks companies reclaiming VAT on fuel payments they have reimbursed to staff if the fuel is not bought by a VAT-registered company.
In conjunction with fleet and fuel management company Arval, Fleet News has launched the FuelWise campaign, designed to help fleet decision-makers deal with the impending change.