biotuning

Basically when you heat the oil - it becomes almost as runny as diesel. It can then be burned in a diesel engine as though it were diesel.

There's obviously more to it than that. Particularly the issue of how to start a cold vehicle using cold thick vegetable oil. There are a number of ways around this issue, which include a) blending the oil with diesel to thin it, b) converting the vehicle to start and run on cold oil (known as single tank) and c) starting and warming up on diesel then switching over to veg when the engine is warm enough (twin tank). There are pros and cons with each method.

Vehicles were not designed to run on vegetable oil so there are a number of issues which should be known and considered before going down this route. Some vehicles are more agreeable to being powered by vegoil than others - generally the older the vehicle, the more likely it is to run on vegoil without problems - many pre '98 cars will quite happily run on vegoil with only very minor modifications, this is where significant financial savings can be made. Other cars of the same vintage have components which are particularly sensitive and may break (especially if run on cold or insufficiently heated oil) requiring expsensive repairs. Newer vehicles typically have higher fuel pressures and complicated engine management systems which make them more difficult to convert successfully. So certain cars will require more extensive conversion and more care and attention to prevent damage.

Next is the servicing of a vegoil vehicle. The service intervals should be reduced - the engine oil and filter should be changed more regularly to prevent engine damage while the fuel filter should be changed more regularly to avoid it clogging. It is good practice to always carry a spare fuel filter in the vehicle...

And finally this leads us on to the fuel. The biggest savings by far, both financially and environmentally are to be had with used cooking oil. This is a case of collecting the oil from a local restaurant, pub, hotel, canteen etc. filtering it to remove the micropscopic particles (to say 5 microns) and pouring it straight into your fuel tank. You need to make sure the oil is 'lightly' used to prevent it from being fatty, watery or acidic. It must also be kept clean and dry. It can take some effort to start with but this can be a slick opperation with the cooperation of an eco-friendly chef. You visit regularly to drop off some empty containers and collect some full ones. Good clean dry oil with no waste at all. The oil is collected for free and since you can use 2,500litres per year before paying duty then it is potentially completely free, a saving of £50 to £80 per fillup in a typical diesel car.

Another option is to buy oil in QTY like you would heating oil (either pumped into your tank or delivered in a 1m³ container) or to buy it at cash and carry or supermarkets (lots and lots of waste packaging, extra journeys and inconvenience to other shoppers who find the shelf empty). The use of new oil may save a 30p or 40p per litre for now but prices are rising as fast as diesel. Also there are wider sustainability issues associated with deforestation and using arable land to grow fuel.

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