This article off ers a method and technical solutions for using vegetable oil fuel as fuel for a diesel engine. The use of rapeseed as a fuel is hindered by its peculiarity, namely, the main problem is the high viscosity and high self-ignition temperature relative to diesel fuel. The authors propose technical solutions that ensure the use of vegetable oil fuel as a motor fuel in diesel engines. For research purposes, a two-fuel system was developed, manufactured and tested, which allows working part of the time on diesel fuel and part of the time on vegetable oil, in particular on rapeseed oil, depending on the engine operating modes. Experiments have shown high effi ciency of the two-fuel system, which excludes negative consequences for the diesel engine. As a result of the research, the team of authors obtained results and conclusions confirming that the dual fuel system allows the use of vegetable oils as motor fuel in diesel engines, while the engine operation is possible in all modes.