Can a diesel engine run on biodiesel?

Biodiesel is designed to be compatible with compression-ignition engines. Many older mechanically injected diesels run on high blends with little trouble, and low blends are already sold at ordinary fuel stations in many countries.

Modern engines are a different question. Common-rail injection systems and particulate filters are sensitive to fuel properties, and most manufacturers publish a maximum approved blend. Exceeding it can affect both reliability and warranty.

Fuel quality is the deciding factor. Biodiesel meeting recognised standards behaves predictably. Fuel that is wet, incompletely reacted or contaminated causes filter plugging, injector deposits and cold-weather failures.