Can I run my car on biofuels such as biodiesel / SVO / WVO?

Not all car engines are suitable for running on biodiesel

You may have decided after reading about some of the environental and motoring benefits of biofuels such as biodiesel that you want to run your car or vehicle on biofuel. Before you rush off and assemble or buy your biodiesel processing unit please make sure that your car engine is suitable. Not all car engines are suitable for running on biodiesel.

The effects of putting biodiesel into a non suitable engine range from the engine simply not starting to much worse such as the destruction of key parts of your engine.

Petrol engines are not suitable for biodiesel or vegetable oil fuel. If you have a petrol engine then you may be able to use bioethanol fuel (some filling stations now offer blends of petrol and bioethanol).

If you have diesel engine then you should be able to run your car on biodiesel although it may require a few minor alterations. When running on Straight Vegetable Oil (SVO) or Waste Vegetable Oil (WVO) then more modifications may be necessary. The effects of these fuels and the potential alterations are discussed below.

Effects of Biodiesel on your engine

The two main areas of concern that using biodiesel can give a diesel engine are both due to it having a stronger solvent characteristic than regular mineral diesel. The flip side to this is that its strong solvent property has the benefit of keeping your engine clean and thus lasting longer.

Older cars tend to use rubber piping in their engines. Any rubber piping in your engine may perish due to the higher solvent properties of biodiesel when compared to regular fossil fuel diesel. To prevent any damage / leaks you should replace any such rubber piping with more resistant nylon / plastic piping.

The fact that biodiesel is a stronger solvent means that it removes a lot of the dirt and grime that has been deposited in your fuel tank and pipes from when the vehicle used mineral diesel. When this dirt and grime is dissolved into the fuel it tends to then clog up the fuel filter with tiny particles. This means that more often or not you will have to replace your fuel filter shortly after starting to use biodiesel.

The good news is that this effect should lessen the more you use biodiesel as it is a cleaner fuel than mineral diesel and so doesn't deposit anyway near as much gunk in your fuel tank and pipes. To be sure you don't get stuck its recommended that you always carry a spare fuel filter in the car, once you've changed it the first time you should recognise the signs if you ever need to do it again.

In winter when temperatures are very low you should consider adding some mineral diesel to your biodiesel to prevent the fuel becoming too thick (viscous) to be comfortably used by the engine.

Effects of SVO and WVO on your engine

Straight Vegetable Oil (SVO) is obtained from crops such as Oil Seed Rape, Palm Oil and Corn. An engine will normally run better on SVO than on mineral diesel as SVO is a cleaner fuel and has a better lubricating effect on the engine than mineral diesel.

The main problem when using SVO is the effect that cold weather has on it. Because SVO is a lot thicker (more viscous) than regular diesel it means that the engine will have trouble starting in cold weather (when the SVO becomes more viscous). To get around this problem there are a few options that can be considered:

Use a Blend or Mixed Fuel that mixes SVO and regular mineral diesel. The colder it is, the higher the proportion of mineral diesel will be required.
The most radical option is an SVO Conversion - Fit a special heater in your fuel tank that preheats the fuel before the engine is started. When the fuel preheater has done its job and the engine is running a heat exchanger takes heat from the cars radiator and uses it to keep the SVO warm when the vehicle is on the move. This is a great use of otherwise wasted heat.
The vehicle can be modified to use a dual fuel system where regular mineral diesel is used to start the engine and then once the fuel is up to temperature the fuel source is switched over to use SVO. Before the engine is switched off the fuel source must be switched back to the mineral diesel so that the fuel lines and injectors contain mineral diesel when the engine is next started in potentially cold weather.

Waste Vegetable Oil (WVO) is normally obtained from restaurants and other food processing outlets. It is very cheap and the ultimate for a 'recycled fuel'. If your car can run on SVO then it should be ok running on WVO. It is however essential to make sure that your WVO is processed properly to make sure that it has similar properties to SVO.

The impact of biofuels on your vehicles warranty

Please note that most of the major car manufacturers do not officially support the use of biofuels in their cars and if you use biodiesel (and especially SVO or WVO) then you may invalidate your cars manufacturers warranty.

What if I have put biodiesel into an unsuitable vehicle

First make sure that you do not switch the engine on. You should then drain the fuel tank and then you would be best calling out a local mechanic.

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