I don’t represent these fine folks but they make a damn fine conversion kit. 

Preface: Rudolf Diesel created the first diesel engine in 1897, and it was powered by biodiesel made from vegetable and peanut oils. In 1900, at the Paris World Fair, he demonstrated a diesel engine fueled on peanut oil. 

Q:
How does the Greasecar system work?
A:
The Greasecar system is a two tank fuel system. The vehicles existing diesel tank and filter will supply diesel fuel to the engine at start up and shut down. After start up radiator fluid will transfer heat from the engine to the heat exchangers in the Greasecar fuel system. These heat exchangers will heat the vegetable oil in the fuel filter, lines and fuel tank. The heat will reduce the viscosity of vegetable oil so that it is similar to diesel and can be injected into the engine properly. When the vehicle is being shut down for a period long enough for the fuel to cool the vegetable oil must be purged from the fuel system and replaced with diesel for the next start up. Purging generally takes around 30 seconds and can be done while driving with the push of the button on you Greasecar controls.

https://www.greasecar.com/faq