This was posted on another forum, but seems to explain things quite well...

Bio diesel doesn't offer the same level of viscous stability as mineral diesel. As I understand it, this makes it prone to causing problems on high pressure common rail injection engines as it becomes too "gloopy" when cold. Also it has a different firing characteristic and so can confuse some highly tuned engine management systems.

I know Fiat, like a lot of manufacturers, recommend not using bio in the multijet but I'm not at all sure if the engine in the Panda is highly tuned enough to make any real difference.

I guess part of the problem is the definition of bio fuel - the cheap stuff sold by independents in the UK is the same as the stuff which can be made at home and is simply conditioned vegetable oil with a small amount of ethanol added. The stuff that the big 4 oil companies sell contains a very high quantity of mineral diesel anyway and so is much more stable (but rather more expensive).

To answer the OP, I'm not sure the Panda engine would run on pure untreated vegetable oil. It works in low fuel pressure, mechanical engines (with a slight alteration of injector timing) but in high pressure engines where the injector timing can't be altered (because it is computer controlled) I don't think it would run very well.

Chris

After many phone calls and e-mails to Skoda customer services, they finally told me that the VRS will not run on full Bio-deisel, due to extra strain on the pump and injectors. You can use a 5% mix of bio-deisel, ie normal deisel mixed with bio-deisel, which unless it offers any performance or economy advantage, won't really be worth buying as it's probably the same cost. My understanding is that bio-deisel has a hight citane level and therefore will give better performance and economy, as yet there are no plans to make Skoda deisels run on bio-deisel, guess at some point they may be forced to?????

the 5% Bio-diesel in France, Belgium etc certainly made my FabiaVRS run a lot smoother with less smoke , with possibly a slight increase in performance

Hi thought this might interest all.

How one garage owner is slashing fuel prices by using ... chip fat

By Chris Brooke

Last updated at 2:18 AM on 29th May 2008

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At 95p a litre, it has to be the cheapest forecourt diesel in the country.

But the secret of one tiny garage's bargain price is not tax evasion or dodgy accountancy. It's all thanks to fish and chips.

The business turns used cooking oil from fast food restaurants into biodiesel capable of running cars safely and efficiently.

It is sold from a single pump and the steady stream of regular and grateful customers all swear by its reliability.

Economy option: A driver fills up at the garage, which is having to cut its opening hours due to huge demand

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Demand at the garage outside York has pushed prices up in recent weeks to 94.9p a litre, but that's still about 35p less than traditional diesel.

As word spreads about the garage's location, demand increases. The business can no longer make enough biodiesel to cope.

Its phones are red hot from hauliers asking about supplies and it has cut opening times from six days to 'two or three days a week' to ensure it does not run out.

It does not need any free advertising. When the Mail visited the company yesterday the manageress was distraught about the implications of national publicity.

'It's a nightmare at the moment, we just can't cope with demand as it is,' said Sally.

'The phone is constantly ringing and as you can see we are very busy with customers who already know us. We definitely don't need any more people turning up.'

They keep their cheap diesel as secret as possible, relying on word of mouth and a single sign showing the price, which is partially obscured from view by a hedge.

The company has collected used cooking oil for 20 years and until recent years cleaned it up and sold it on for industrial use.

Now it sells about 60,000 litres of biodiesel a month to motorists.

Vans tour the region collecting used cooking oil from fish and chip shops, cafes, restaurants, hotels and schools. The oil is free as they are effectively providing a waste collection service to caterers.

Back at the site near York, which looks more like a farmyard than a garage or business, the oil is put into a large tank and filtered to remove bits of food.

The biodiesel contains 80 to 90 per cent vegetable oil, 10 to 20 per cent alcohol and around 1 per cent is a 'catalyst'.

'The process takes a couple of days,' said Sally. 'The alcohol provides the spark to make it go. Our biodiesel can be used to run any diesel engine. It is reliable and good quality and you don't need to add anything, though some motorists prefer half cooking oil and half normal diesel in their cars.'

The company has to pay VAT and tax of 30.35p a litre, 20p less than for normal diesel.

The customers certainly seem happy. Engineer Simon Melton said: 'I've been coming here for a couple of years. Most people say this kind of fuel knackers the engine, but my Audi runs smoothly and I've never had a problem.'

Malcolm Jackson, 58, who drives a car repair truck, said: 'It's usually £100 to fill this vehicle up and it only costs £60 here.'

There is a booming cottage industry of people making their own 'home brew' biodiesel from waste cooking oil. With the help of special equipment and the addition of a several chemicals, anyone can do it.

The cost is said to be only 15p a litre. Rules state you can make up to 2,500 litres a year for personal use without telling the taxman.

Magic mix: The single biodiesel pump

The exhaust smell can vary and depends on the type of oil. Some users say it gives off a 'chip shop odour'.

The borough of Richmond, in South West London, this month put out a tender for a £3.5million contract to run its 300 council vehicles on recycled vegetable oil for the next three years.

The council believes it could save £100,000 and reduce greenhouse gas emissions by hundreds of thousands of tons.

UK fuel suppliers are now legally obliged to ensure that at least 2.5 per cent of the petrol and diesel they sell comes from crops.

Most diesel now contains a small percentage of biodiesel, usually made from soya or rapeseed oil. But few garages sell diesel made almost entirely from vegetable oil.

Tesco garages sell diesel which typically has about 5 per cent biofuel. The York garage's contains up to 80 per cent vegetable oil.

The first diesel engine, built in August 1893, was powered by peanut oil. But during the 1920s manufacturers altered their engines to use the lower viscosity of petrodiesel.

Revenue and Customs declined to comment on an individual business, but said tax rates had changed to 'encourage' biofuels similar to conventional diesel.

OR read it on How one garage owner is slashing fuel prices by using ... chip fat | Mail Online

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TBH I have real issues with Biofuels morally.

The rising food costs due to farmers growing crops for biofuel rather than food being one. It's also incapable of replacing diesel as there is no way of producing enough to refine into useful fuel.

TBH I have real issues with Biofuels morally.

The rising food costs due to farmers growing crops for biofuel rather than food being one. It's also incapable of replacing diesel as there is no way of producing enough to refine into useful fuel.

Hmmm. That's a very blinkered view, which only seems to look at a one of the multitude issues. Do you care to expand?

Real bio users will be using recycled WVO which is just reusing something that would have been disposed of. If we all made a few changes to the way we do things then a good balance could be struck. It will never happen though because people are too greedy.

Hmmm. That's a very blinkered view, which only seems to look at a one of the multitude issues. Do you care to expand?

Real bio users will be using recycled WVO which is just reusing something that would have been disposed of. If we all made a few changes to the way we do things then a good balance could be struck. It will never happen though because people are too greedy.

Reusing chip fat (etc) gets my vote.

However, that's not where most of it is coming from. Farmers are being lured by cash which can be greater than normal crops or even subsidies.

It has to be grown somewhere, but I'm not prepared to pay higher costs on basic foods because of it.

Reusing chip fat (etc) gets my vote.

However, that's not where most of it is coming from. Farmers are being lured by cash which can be greater than normal crops or even subsidies.

It has to be grown somewhere, but I'm not prepared to pay higher costs on basic foods because of it.

It is a contributary factor to rising food costs but the main cause of this is the price of transport...

It's one big nasty vicious circle. People tunr to Bio because mineral it too expensive and it all comes round again :( I buy WVO with a few additives and use it diluted but my supply has recently been cut off due to my supplier having licence and tax issues. CAE make it as difficlut as possible to be an independant manufacturer using WVO. It almost as if they don't want you doing it....

There is only one answer. Reduce the number of cars on the road. (Although thinking about that we would have to pay the tax not paid by them in another way :(

I use to buy 100% biodiesel/ veggie fuel from Liverpool and put it in my '51 plate Fiat with no bother but I don't think I would put it in new CRD engines.