This study looks into the density gradients in mixes of diesel and vegetable oil to determine how they might affect injection dynamics and combustion kinetics. The main emphasis is on how the vegetable oil volume ratio is increased in order to control the drop in viscosity and energy content that results from a reduced calorific value. Because fuels derived from vegetable oils usually have a high viscosity, mixing them with diesel can significantly reduce this problem. Optimizing the disintegration of fuel droplets guarantees enhanced combustion efficiency and mitigates the possibility of nozzle blockage. In order to maximize the effectiveness of these mixes, the study highlights how crucial it is to balance their viscosity as well as energy content. Through an examination of various characteristics of combustion of diesel–vegetable oil blends in an industrial fuel burner, the study seeks to offer guidance on how to improve fuel economy and reduce emissions. The outcomes may aid in the creation of more economical and environmentally friendly fuel alternatives for applications in industry.