Contaminated Supermarket Fuels

Having seen the BBC news reports on the incidents occurring all over the country, I find it quite unbelievable that the chief spokesperson for the Petrol Retailers Association did not have enough knowledge about the operation of the Oxygen (Lambda) sensor to be able to point out to the BBC interviewer that ethanol 'contamination' cannot cause damage to the lambda sensor.

Ethanol burns in just the same way as petrol, even cleaner than petrol in fact, and does not affect the lambda sensor in any way. this is clearly demonstrated by the fact that in countries where ethanol fuels are encouraged and readily available (eg.Brazil), a different type or specification of Lambda sensor is not required. It is also a pointer to a lack of understanding of the issues involved that he stated in his last 30 years of experience he has never seen anything like this, despite the fact that Oxygen sensors have only been a standard fitment across all vehicles in the EU since the mid Nineties.

Ethanol

A small amount of Ethanol is added to all commercially available petrols in the UK. Ethanol is also used as a cleaning agent to wash out the petrol storage facilities between refilling, and some of this residue will inevitably end up in the fuel. Lambdapower can state categorically Ethanol poses no threat to any part of the fuel management system on your car. The petrol companies are allowed by law to sell fuel containing up to 5% Ethanol, 95% Petrol. Any more than 5% Ethanol and the fuel must be labelled as 'Biofuel', as the Ethanol is sourced from renewable plant resources. Normal vehicles will run happily on fuel containing up to 10% Ethanol; any more than this and changes are needed to the engine.

The only effect of these small levels of Ethanol in fuel is that the injection system may have to compensate by increasing the injection pulse by a tiny amount. No Ethanol is found in Diesel fuels as it is not compatible with compression ignition that occurs inside a diesel engined vehicle.

Lambda contamination and malfunction

From the initial reports we at Lambdapower were instantly suspect of the blame being pointed at Ethanol for vehicle running problems. Elsewhere in our tech guides we identify the main causes of Lambda contamination as follows:

• trace amounts of metals in the exhaust gases from infrequently changed engine oils
• silicone contamination from inappropriate engine gasket sealants

Both these contaminants have the effect of coating the ceramic element located inside the sensor, preventing it from operating effectively. It has since transpired early on Friday 02 March that silicone contamination could well be the cause of the reported O2 sensor failures. This means that silicone contamination from an outside source (eg. contaminated fuel supplies) has to become a possiblity that we must consider, both with silicone and other compounds containing trace amounts of foreign metals.

Insurance compensation for cost of repairs

We hear the Association of British Insurers (ABI) have stated that if you have a comprehensive insurance policy it may be possible to reclaim the costs of repairing your car if it can be shown that fuel contamination, and not normal wear and tear was the cause of the Lambda repairs having to be carried out. It would seem to us that the burden of proof rests with the motorist which can cause problems but it remains to be seen how this will progress and we will keep you informed.

Fuel quality issues

Without any particular disrespect to any of the major supermarket chains, we have always maintained that it is inadvisable to refuel your car at a supermarket filling station unless absolutely necessary (reference our long-standing diagnostics section here). In order to keep prices keen, along with subsidy from the grocery arm of the operation, it is inevitable that the petrol will be sourced from less advanced refineries, and owners of vehicles that are "fussy" about quality of fuel will attest to this. We recommend (and there's no sponsorship endorsement here!) BP or Shell, although it must be pointed out that this does not necessarily safeguard against a similar occurrence with one of their suppliers.

What to do now

So what to do? Well, read our site. This will give you ample information on the causes and effects of Lambda failure. If you suspect your car of having running problems associated with Lambda failure we cannot guarantee absolutely that it will rectify the problems, but if poor running symptoms have appeared in the last few days, and you regularly fill up at a Supermarket forecourt it seems a strong possiblity.

Also beware of your garage making random stabs in the dark - plug leads, ignition coils - these items have failure modes quite distinct from Lambda failure and should not be confused.

The supermarket chains implicated in the contaminated fuel incident are Tesco, ASDA and Morrisons although the supplier of the fuel to these supermarket chains, Greenergy, would most likely be to blame for any contamination that may have occurred. The storage and distribution is looked after by a firm named Vopak Terminals. All the companies mentioned here are I am sure doing their best to isolate the cause of the alleged contamination and until the results of any pending investigation are released no firm conclusions can be drawn.

02/03/2007

Update 06/03/07

Tesco and Morrisons have both now admitted there were high levels of silicone found in some of the tankers at the Vopak storage facility, which has led to contamination of fuel supplies to their supermarkets.

Silicone Additives

Silicone is used as an additive in diesel fuels to prevent excessive foaming during transportation and whilst filling your car up. It is acceptable to use storage vessels for different chemicals, even ones that are incompatible, as long as the tankers are washed out first. A volatile solvent can be used to do this such as Ethanol.

However, increasingly stringent European directives for the reduction of Hydrocarbon emissions, which includes uses of chemicals such as Ethanol, has to beg the question whether the amount of Ethanol used to clean the tanks has been significantly reduced, perhaps rendering the process ineffective. Or maybe a less effective method that avoids the use of volatile solvents is now used.

Compensation for Repairs

Tesco and Morrisons have both now said they will compensate "reasonable costs" of repairs to your vehicle as long as you can convince them that their fuel was to blame. This will involve a receipt for both your fuel purchase and for the cost of repairing your car, which they will restrict to reimbursement for fuel system components, or possibly only Lambda sensors will be eligible.

As stated before the burden of proof still seems to rest with the motorist. Tesco won't be able to justify the cost of individually testing each vehicle's fuel system so it looks as if a receipt will do, unless you have paid in cash for your fuel, and have no receipt of any kind in which case the supermarkets have said they will examine each case in detail.