Using vegetable oil as fuel in diesel engines isn’t a new idea. Rudolf Diesel’s first engines were built to run on peanut oil for the developing world, which had no petrochemicals industry. Running your modern diesel car or van on veg is just going back to what the designer intended.
An ordinary diesel engine cannot run on 100% pure vegetable oil without conversion. Veg oil is too thick and gloopy to get through the fuel pump and injectors. Conversion is moderately expensive and is quite a commitment, so we’ll leave that to the experts.
Instead, we’ll try to thin down the veg oil so that it works correctly in the engine. There are two ways to do this: mix it with something, or convert it into biodiesel.
There’s no complicated science behind it:
The easiest way to do this is to run your tank almost empty. Then when you pop to the supermarket, fill up with diesel, and then add the veg oil. The drive home mixes it all up nicely.
How much veg oil should you use? Start with a light blend, and increase each time you refill. That way, if you notice your car sputtering, you know you’ve hit the limit and should use less next time, and you can top up with regular diesel to thin the mixture back down.
The article describes how vegetable oil should be introduced gradually, what types of oil to use (rapeseed is the best since it’s the runniest), and legal issues (the government will probably want to tax its use).
I’d love to do this, although even if I had a diesel I be hesitant to try it, fearing I’d screw the engine up.