SVO burns well in many diesel engines. But due to its relatively high viscosity SVO leads to poor atomisation of the fuel, incomplete combustion, coking in the injectors (as a hot engine cools), ring carbonisation, and accumulation of fuel in the lubricating oil.
To use SVO in a car, one needs a tank for vegetable oil and a separate tank of diesel (petrodiesel or biodiesel) to be used during starting and stopping of the engine, and an electric valve that allows transfer to the SVO tank. One also needs to pre-heat the oil or the viscosity will be too high.
To be used without a special tank and modifications in a petrodiesel engine, vegetable oil (vegoil) must be transesterified to biodiesel.