If you own a diesel car or truck, the idea of being able to run your car off biodiesel or vegetable oil can be alluring. Just think: No more gas pumps… no more paying for gas. But while an unmodified diesel engine can burn biodiesel, or even vegetable oil in principle, converting your engine with a few simple modifications can optimize the performance of your biodiesel engine and forestall wear and tear caused by the thicker fuel.

What is Biodiesel?

Biodiesel is a less viscous and more easily burned fuel made from vegetable oil. It is made by removing glycerin and transforming the liberated fatty acids into methyl esters. Any sort of straight vegetable or seed oil (SVO) can function as a fuel due to their high chemical energy values. Used vegetable oil, called WVO (Waste Vegetable Oil) can be sourced from restaurants, as an alternative to new vegetable oil. You will have strain the restaurant oil in order to get the bacon bits and other leftovers. And I can’t advise eating those.

Why do you need to convert your engine in order to use Biodiesel or SVO/WVO?

The biggest problem with unmodified vegetable oils as a fuel is that they tend to “gel” in cold weather, which creates problems in delivering the fuel to the engine, and can strain the filter and fuel injection system. Additionally, straight vegetable oil burns at a higher ignition temperature, making it harder to burn off in the engine.

Biodiesel itself is not entirely free of cold weather issues relative to ordinary petroleum diesel, and it also tends to degrade the rubber hosing inside the engine over time.

What are Biodiesel Conversion Kits?

In a typical conversion kit, a second tank in the trunk of the car to hold biodiesel or SVO/WVO will be installed in addition to your old petroleum diesel tank. The second tank contains a heater to preheat the fuel to “loosen” it, as well as optimize it for burning more effectively in the engine.

What are the pros and cons of converting to biodiesel?

Biodiesel or SVO/WVO is “carbon neutral”, since the carbon released on combustion is balanced by that absorbed by the plant which produced the oil as it grew, and due to the lower cost of vegetable oil, you can recover the cost of the conversion though savings on fuel. Unfortunately, though, making such a conversion can void your warranty if you own a new car which is still under warranty.

It is also critical to remember that while you won’t be paying for gas any more, you will have a new hobby as a biodiesel processor. You’re going to need a workspace that is extremely well ventiliated, plus a lot of tolerance from the other people who live in the house. Biodiesel production is messy.

Conclusions

It is not surprising that diesel engines can run easily on plant-based oils, since Rudolph Diesel himself intended his first engine to run off peanut oil. The modern diesel engine is not substantially different from that model made over a century ago, and newer technology can make the diesel engine run off fuels other than petroleum-derived diesel fuel even more effectively.