Fleet News

Diesel biofuel content suspected cause of unexpected winter breakdowns

Thousands of diesel car drivers could be faced with a surprise breakdown brought about by an issue with the quality of diesel fuel being sold on forecourts throughout the country, reports the RAC.

The problem affects diesel cars but is not specific to any particular vehicle age or make.

Data suggests the issue is more prevalent in eastern parts of England and Scotland, with the greatest concentration of breakdowns occurring in the North East, and can arise from diesel purchased from any type of fuel retailer.

The RAC is working with the fuel industry and motor manufacturers to help find the root cause of the issue which results in diesel fuel filters becoming blocked by the formation of a gel-like substance in the diesel.

This can block the fuel filter thus starving the engine of fuel and may result in the engine not starting or in a loss of power. The amber engine malfunction indicator light might also show.

Whilst the primary cause of the issue is still under investigation, one of the areas receiving closest scrutiny is the up to 7% biofuel content which by EU law has to be added to all road diesel.

Sometimes in the past, some owners of diesel vehicles found that their diesel was “waxing” in the very coldest weather.

Nowadays, however, diesel produced for UK winter use is formulated with additives to prevent waxing.

The symptoms of the current problem are similar to those of waxing but the cause appears to be different. And, unlike waxing, when the weather warms up the gel does not dissolve back into the fuel which means a new filter has to be fitted.

RAC patrols have been dealing with the inconvenient and costly consequences for motorists for some time.

The issue affected only a small minority of motorists throughout last winter with the largest number in March, but the problem disappeared over the summer.

However, in November the RAC attended almost 600 such incidents, the highest number of blocked fuel filters so far this winter.

The number of RAC breakdowns would equate to around 2,500 vehicles across the whole UK car parc.

RAC technical director David Bizley said: “Motorists were often led to believe that there were differences in the quality of fuel sold at supermarkets compared to other retail outlets which is just not the case as all diesel, wherever it is sold, is produced to the exact same standard specification.

“Having diesel fuel filters changed at the right service intervals is clearly important because a failure to do so can lead to starving the engine of fuel; but from the number of breakdowns we have attended this cannot be the primary cause.

“The industry is working extremely hard to find a solution which is good news for motorists.

“Neither the fuel producers, nor retailers, nor the motor manufacturers saw this problem coming last year.

“The current specifications for all fuel sold at the pump have been developed over many years and continue to evolve based on a combination of test programmes and field experience.

“Specifications have been further tightened since the problem was first reported, but it’s clear that we still don’t fully understand all aspects of the underlying cause. Motorists will share the hope that progress is rapid so that the associated risk of inconvenience and expense is removed.

“The fact these issues are far more prevalent in the east than the west suggests that supplies to these areas have characteristics that are not common to the whole country.

“We urge the fuel industry to continue its efforts to identify the source of the problem and find a permanent solution to it.”

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  • A J SHAUL - 13/12/2013 11:19

    I have been experiencing this problem for 5 months. Repeated draining of the fuel filter fixes the issue for about 300 miles, then it returns. The replacement of the fuel filter also fixed it for about 300 miles. The fuel collected from the filter did not have any particulate or water contamination on any of the occasions when drained. It appears that a high surface tension dissolved impurity is in the whole fuel system which is creating an invisible barrier film on the filter element surface. I have experienced this many years ago in the chemical manufacturing industry in fractionating and filtration processes. this caused all filter elements to have to be changed and the whole plant to be drained and thoroughly cleaned to overcome. When the problem occurs there is a very large pressure drop across the filter between the incoming and outgoing sides of the elements. With the current car filter problem if the plunger on the top of the filter is depressed to cause a pressure build up and then the engine restarted the fuel starvation is again temporarily overcome but it returns again after the high tension film again blocks the filter.

  • Buckets - 13/12/2013 12:30

    As someone who has manufactured biodiesel processors in the past and carried out extensive tests I know what the problem is. When processing new or waste oils to create the biodiesel it is best to use stock material that is liquid at the temperatures in the country in which it is combusted. Sunflower and Rapeseed for example are liquid in our winter. Palm oil is solid even in our summer weather (mostly). Biodiesel manufactured from palm oil which is very popular in the UK by caterers, tends to revert back to it's parent state. Winterising helps, but does not fix the problem. If fuel manufacturers are blending this into UK biodiesel then this can result. Although the fuel will apparently be up to EN590 specification. You can get away with it in summer months as B7 (indicates concentration of biodiesel to 93% fossil diesel) is a low enough concentration work around it. Most modern diesels also deliver unused fuel from the injectors, back to the tank, picking up latent heat from the injection system. In winter it's just too cold to cope. Manufacturers cannot afford to hold large volumes of palm oil to one side until the summer, so I don't know how they will fix this.

  • Paul - 13/12/2013 13:30

    I would like to know if this problem is across all fuel suppliers or just your local supermarket!

  • Edward Handley - 13/12/2013 14:26

    The vapour point for ordinary diesel is around 65C but is much higher for biodiesel, usually in the range 90 - 120C depending on the type of oil the fuel is made from. Truck operators had a huge problem in the 1980s as the Government allowed the oil companies to refine to a lower standard which mean fuel contained a lot more water which waxed up when it got cold. The problem was severer for trucks the buses and cars because their fuel tanks are usually exposed. The problem was made worse by dirty filters but could usually be solved with anti-waxing additives or by fitting heated fuel lines. The article implies that the problem is affecting diesel cars and LCVs rather than trucks and buses - it would be interesting to have this confirmed. If water content is not the problem this time as the diesel turns to gel rather than wax it might well affect cars and LCVs more than trucks because the filters are a smaller and possibly finer.

  • Mike Fleet. - 21/12/2013 09:55

    thank yoiu for your report, however I am now waiting for my 14th stoppage due to my filter being clogged with Tesco diesel, the first was on a roundabout, but she fired up after the third attempt to start. the second stoppage wouldn't restart, so AA were called, 40 min wait on M2. got home she fired up to get from the pick up onto the drive, third M2, 4th & 5th M2, 6th leading on to a very busy dual carriage roundabout on the offside lane, and all of the others on the M2 Now trying Super diesel from Esso. Hopeful, just to say my car is serviced properly, 2.5 Chrysler Voyager CRD. and restarts every time so far after 5 10 min wait.

  • Colin lawson - 11/01/2014 07:25

    I have had no problem normally with this issue (having always bought my diesel at Sainsburys),, but after buying some fuel at tesco recently I experienced this problem several times on a journey of over 100 miles. The symptoms were when putting throttle pedal to the floor engine lacked power and thought it was going to cut out.I,m not going to tesco for my fuel again.Next stop garage to have filter to be replaced/cleaned!!

  • Terry Butcher - 11/03/2014 10:25

    Mondeo 2005 diesel glow plug comes on goes into limp mode. is this a bio fuel problem ? Stop and restart then its ok until the next time

  • Terry lafferty - 14/04/2015 16:19

    I recently purchased a hyundai ix35 and was told by the sales staff not to buy my deisel fuel from supermarkets as it contained more biofuel whitch blocks the filter.I was told that my 5 year warranty would not cover any filter problems.

  • Terry lafferty - 14/04/2015 16:20

    I recently purchased a hyundai ix35 and was told by the sales staff not to buy my deisel fuel from supermarkets as it contained more biofuel whitch blocks the filter.I was told that my 5 year warranty would not cover any filter problems.

  • Paul - 17/08/2016 15:52

    As a user of two diesel cars i think the problem lies with th EU not doing research as we the tax payer can pay for any probs . If you disldge sludge in your vehicle tanl imagine how much is @ the fuel dtation ! this then ends up in our tanks ! Peugeot say change fuel filter by two years if arduous service , to much traffic calming and jams whwn driving . I use a very exspensive additive on the SGV and works so used on hard to start van 24 hrs later ok but will get new filter on booked service as sure its this again ! Not hard to do when in garage so should be a must yearly ? .

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