Biofuel (WVO) project log

The beginnings of an idea
My major is in sustainable development. Needless to say, buying a car had never been an option for me, at least, not until our first baby was born.
Living in the far north East corner of Kyoto, has the benefit of clear cool air and on-the-doorstep access to Hiezan forest. However, this comes with a cost; a long gradual climb finished off by a short but extremely steep ascent, which only a small percentage of the local population can regularly conquer by bicycle. So, with our house positioned as it is, and the growing weight of our daughter on the back of our bikes, the need for a car steadily grew
Over the past year, we were lucky enough to car pool a small k-van with some friends but this was only a short-term answer. By the summer of 2007, I was faced with the realisation that, as I saw it, I would have to fork out some real cash, and get a Toyota hybrid Prius. However, after a couple of months of prevarication, I started thinking more about the opposite end of the spectrum, opting for an old, cheap car, that might allow me to drive with an even smaller and less guilt-ridden carbon footprint experience than even a Prius could offer. And, it was more of a challenge - to run a diesel car on waste vegetable oil (WVO). Also referred to as SVO (straight vegetable oil) it is different than biodiesel in that, as the name suggests, only oil is used as fuel and no chemicals or heating is needed to process the fuel. This was the way I wanted to go, and in September 2007, my WVO project officially started.

Stage 1: Deciding on the conversion to adopt There are two main WVO systems to choose from; the single-tank or the two-tank systems or conversions. While the first one is cheaper, the second, despite being more complicated and expensive, is much more robust by allowing your car to run on oil even in very cold conditions when oil can become too thick for the engine to burn. I chose the two-tank route. As the name suggests, it involves having a second fuel tank added. The main tank is then used for your oil, and the second smaller tank for diesel – and as I found out later – useful for emergencies when the oil system fails. The conversion works by allowing you to start the car using diesel, and when the engine is hot enough, to switch over to oil. When coming to the end of your journey you just switch back to diesel and purge the engine of oil ready for the next trip.

Stage 2: Find a car This took a lot of research, because until this time, I simply had no interest in cars or knowledge about models and their workings. Eventually however, I summised that Toyota and Nissan 4X4 (SUV) models were suitable and at the end of September I picked up my new 1993 Toyota Hilux Surf which I have to admit I really like. After years of despising all oil-guzzling, CO2 belching 4x4s that passed me by, I still find it hard to believe I’m now driving around in one myself. Because it was September and still warm, I decided to risk running the car on a diesel oil mix even though no modifications had been done. At first, it is a very strange experience to pour oil into your diesel tank and a bit nerve-racking driving it for the first time using oil. All the time I was expecting it to grind to a halt. This never happened though, and in hindsight my 40-50% oil to diesel mix was probably over-cautious and with the September temperatures still around 25C, a 90% mix would have probably been equally effective.

Stage 3: Find a conversion kit If you are experienced, you could purchase all the parts needed to convert a car to run on WVO yourself. The other alternative is to find a suitable Internet site which offers conversion kits. Prices vary a lot but for me I based my choice on the most non-commercial and friendly looking operation. This turned out to be a good choice and I received a great amount of support from my supplier, Marcus at, based in Australia.

Stage 4: Find a mechanic As soon as I ordered the kit I then went looking for a mechanic. The key is finding on who is local and willing to try and install it. I say try, because I think very few mechanics in Japan are aware diesel engines can be run on waste oil, or at the very least, are very sceptical that it can be done by private car owners. And certainly, you’d be very lucky to find one who has actually had any experience with converting cars to run on WVO. A local mechanic is important because before your conversion is fully operational, you will almost certainly be making many short trips to the garage to iron out the inevitable glitches that will arise as you first start using your new system. No one conversion will be the same. Even though you may buy the same kit, fitting it requires the individual skill and imagination of the mechanic and the addition of his or her own parts to turn the kits into fully workably systems.

Stage 5: Getting an oil supply At present with very few if any other people doing the WVO thing, there is currently no competition for what is essentially a free fuel; the waste vegetable oil used by restaurants. As a result this stage was probably the easiest to do. I now have three small restaurants which every week or two ring me up to collect their oil. This supplies me with more than enough oil for all our current driving needs.

Stage 6: Getting an oil filtering system going This was responsible for the most sleepless nights spent over this whole project. There were so many forums giving so much advice, ideas, and warnings, that it left my head spinning. These sleepless nights were also broken up by daytime trips to many different home centres looking for things which could conceivably be used to make a filtering system. As all home centres sell essentially exactly the same limited choice of items, many of these trips were inevitably a waste of time. In the end my filtering system consists of some clear hoses, 20 litre plastic water containers, filters ordered from e-bay, old clothes for rags, and a cut up PET bottle for a filter holder. The aim is to make a system that allows you to filter oil three or four times, each time using a progressively finer filter. Depending on the quality of the oil you are getting, it may also be necessary to remove any water content by a process of settling and siphoning. Luckily, the oil I am getting has little if any water in so my oil processing is limited to testing for water content and then filtering the oil so that it is clean enough to put into the car.

Stage 7: Getting the conversion done This involves passing translations of web site information and schematics of the kit you have recently received delivery of to your mechanic who, for the next month or so, will most likely become the most important person in your life. After leaving your car, a box of parts and the afore mentioned papers with my skeptical but willing mechanic, I only had to wait a week before the car was ready to be picked up.

Stage 8: Field trials It was again with in trepidation that I first started driving the car using the new system this time it was November and getting cold. The first sign of trouble was that when going up hill it would loose power and unless I switched back to diesel, die. Luckily the switch back to diesel only takes a few seconds to come into effect and so works in effect like a turbo switch - to get over hills. Of course this wasn’t ideal as it meant I was still using diesel much more than I wanted. The first trip back to the garage was to fit a fuel pump. This didn’t make much difference. It was only when we went on a long drive to Shiga during a snow storm that I realised the system was not being allowed to heat the oil because of wind chill under the car where all the system filters, and fuel lines are installed. After insulating these during another trip to the garage the car, for the first time, was running well in very cold weather on 90% oil. I still add 10% kerosene to winterise the oil and of course, diesel from the second tank for starting the engine and running it for two to three minutes until the engine and oil heating system are warm enough for the oil to be heated.

And now… Although I’m still wary about possible problems with the system, I’m finally starting to enjoy driving around guilt free in a car that is essentially fossil-fuel free. I now hope to get involved with helping other people wishing to do the same. If you are one of them, you can find more information and useful links on this site or e-mail me at