Vegetable Oil as Diesel
Adding Vegetable Oil to Diesel Engines
With the recent rise of Biofuels one type of fuel that often crops up is the Straight Vegetable Oil addition to Diesel fuel. This is very different to the normal Biodiesel which requires a lot of clever chemistry to turn the vegetable oil into something more like Diesel. Straight Vegetable Oil (SVO) is quite simply achieved by pouring vegetable oil into your fuel in your tank! (with some modifications to your engine first..)
Vegetable oil will in theory burn well in your engine, the problem is the viscocity of the oil is generally much higher than diesel and can even practically set in very cold climates. For this reason if you wich to run your car of Vegetable Oil you will have to ensure that the engine is modified to preheat the oil before it is sucked into the engine. Failure to do so could cause the fuel lines to become clogged or the fuel pump itself could even become damaged. You can also just add a proportion of Vegetable Oil to your car instead of going for the 100% option, this will reduce the heating requirements on the fuel and you may be able to run with no engine modifications, especially in the summer. It is not something that we recommend trying without getting professional advice first!
Basically before using Vegetable Oil in your car you must ensure that the oil is heated to 80degree celcius before entering the fuel pump, this can be achieved either with electrical heating or by using heat exchanged from the engine itself
Also the vegetable oil must not cool down inside the pump or the fuel injectors, which means that the engine must be pretty well pre-heated before using the vegetable oil. One way to do this is to run the car on Diesel for a while beforehand and then switching over to the vegetable oil supply using a solenoid switch. This means that car will have one vegetable oil tank and one Diesel fuel tank.
For details on which car engines are suitable for running using Straight Vegetable Oil take a look at this Vegetable Oils Fuels Database (independant site)
To re-iterate, the safest way to use vegetable oil in your car is to have a properlly installed two-tank system where the oil is pre-heated and you run the car on pure Diesel (or Biodiesel!) during startup (warm up) and before shutting the engine off (to flush the system). You can try just mixing the straight vegetable oil with Diesel or even adding an organic solvent to try to thin it down, but, you are probably heading for trouble if you do this. There are also kits out there that cmopletely modify the engine to take work just of Vegetable Oil without any secondary Diesel tank. This isually involves replacing the injector nozzles, changing the glow plugs, adding heating elements and different fuel filters.
Tax on Vegetable Oil
The tax or fuel duty you have to pay on Vegetable Oil when burnt in your car varies from country to country. In the UK the law has changed several times in the last few years. Prior to 2005 you had to register the fuel and pay 28.35p per litre of vegetable oil used, then in 2005 it was changed to 48.35p/litre which is the standard fuel duty to pay on Diesel. Then in 2006 it was changed again so that there was an exemptio on using less than 2500litres per year, anything after that and you have to pay the 48.35p/litre. To put this in context that is around 40 tanks of fuel for an average car of 60 litres. For average driving this would take you around 8000miles. Given that if you use over 2500 litres of vegetable oil a year you need to register and pay full duty on the fuel you may be better off diluting the oil down with Diesel or simply only using the Vegetable Oil in the summer months.
Submit your Own Diesel Prices
If you are reading this then you probably own a Diesel car and are horrified by the amount you are paying to fill up. If so use the map below to find cheap fuel in your area, please also update the map with any Diesel prices that you know.