WARNING 1 – In the UK it is not legal to run a car on cooking oil as it is a waste product, and it is not considered a suitable fuel for vehicles. The UK Vehicle Certification Agency (VCA) does not certify cooking oil as a suitable vehicle fuel and the Department for Transport does not permit the use of cooking oil for vehicles. Cooking oil is also not a suitable fuel for vehicles due to the potential for engine damage, as it has a different viscosity to diesel and can cause problems with the injection system which can lead to engine failure.

Warning 2 – Before converting your car to run on used cooking oil, it’s important to check with a mechanic to make sure your car is suitable for the conversion. The mechanic will be able to assess the capabilities of your car and advise you on what modifications may need to be made. They will also be able to tell you if your car is compatible with used cooking oil and what steps you need to take to make the conversion. With the help of a professional mechanic, you can ensure that your car is running safely and efficiently on used cooking oil.

I believe that since writing this post, there are now places in the UK where you can buy Bio Diesel which can be used in Diesel Engines and is still cheaper than topping up your car with standard Diesel. Do your own research if you plan on doing this.

Running a Diesel Car on Used Cooking Oil

It is possible to run a diesel car on used cooking oil, but it is important to note that it is not a process that should be undertaken without proper preparation. Since used cooking oil contains impurities that could damage the engine, it is important to make sure that the oil is filtered properly before use. Additionally, the car needs to be set up for running on vegetable oil, as the viscosity of the oil is different from diesel fuel, and the car needs to be able to handle the added strain. Once the car is set up properly, it is possible to run it on used cooking oil, although it is important to note that this is not a reliable and consistent power source.

What Type of Diesel Engines will Run on Cooking Oil

I did test this for quite a while on two vehicles, both were very old turbo Diesel engines. The first vehicle was a Ford Escort and then the next vehicle was a VW Sharran. At the time, I was not really too concerned if it all went wrong, as I knew that they were old and would not be sold on. Their final stop would be the scrapyard. Since doing this experiment, I was advised by a mechanic that older type Diesel engines were better for running on old cooking oil.

New or Old Cooking Oil to Run a Diesel Engine

When I first started doing this experiment, I used new cooking oil. I would buy a large drum, half fill the vehicle with Diesel and then add the cooking oil. I just figured that the Diesel and cooking oil combination would save some money and still give me the same consistency. Gradually over time my confidence grew, I was using more cooking oil than Diesel.

One day, I was sat in the pub having a pint, when a man came in with one of those two wheel hand trucks, he went into the kitchen and came back out with a large barrel of cooking oil. I bought him a pint and had a chat about him collecting used cooking oil from the pubs etc. It turned out that he was not too far away from me and suggested that I come over and have a look at his operation. Part of the process was that he would filter the oil into large vats. I asked him if I could buy some of the oil from him and he said it would cost me £0.35 a litre. So now I had a source of filtered old cooking oil.

Diesel to Used Cooking Oil Mixture

Over time I experimented with the mixture, I wish I had taken more notes at the time. I would gradually increase the amount of old cooking oil and decrease the amount of Diesel that I was using. Over time the diesel became less and the old cooking oil increased, as I did this I would monitor the performance of the vehicle. I do also recall experimenting with adding white spirit in order to keep the cooking oil a bit thinner.

Cars Performance on Using Old Cooking Oil

I did find the the more cooking oil I used the more the exhaust smelt like an old chip shop. When it came to power, I did notice that the power of the engine seemed slightly lower, but not enough to think it was a waste of time. Maybe there was no power difference, just in my mind I was looking for something to fault it on. One thing that I did notice was, the engine did seem to run slightly hotter. Having said that though, the temperature gauge was still well within the parameters of not having to worry about it. Once issue that did come up was, I would have to change the fuel filter slightly more often than when I was using just Diesel. This was only on average once a year, so not a problem in the grand scheme of things.