Removal of free fatty in neem oil using diphenylamine magnetic mesoporous silica-15 for biodiesel production presents various ways of preparing biodiesel with clear explanation of challenges each method has.Explicitly it shows experimentally step-by-step procedures on how to prepare it from different varieties of feed-stocks.Criteria for assessing the quality of the synthesized biodiesel and the conventional petroleum based diesel was also presented.Possible effects on diesel engine performance and the way to address such challenges were also among other things discussed.