Biodiesel is an alternative and renewable diesel fuel, can be produced from diverse kinds of vegetable oils. The biodiesel effects on engine performance and emissions vary as the source of oil changes. In this study, castor oil biodiesel (CAB), coconut oil biodiesel (COB) and waste cooking oil biodiesel (WCB) were produced by transesterfication approach and blended with conventional diesel fuel (CDF). The volumetric blending ratios of biodiesels with CDF were set at 5, 10, 20, and 30. Tests were carried out under different loads and speeds which simultaneously change. Change in engine performance and emission characteristics against speed or load were investigated on a turbocharged DI compression ignition engine. Viscosity, oxygen amount in fuel, length of hydrocarbon chain, cetane number, biodiesel amount in fuel, engine speed, load have been considered separately, for better consideration of the effects of each parameters, in this study they were considered and compared in similar laboratorial condition. Based on the main effects of load and engine speed on emissions and engine performance, it this study both of them were considered simultaneously. Totally, the experimental results indicated that the best performance and emission characteristics belong to WCB and COB blends respectively fueled in the diesel engine. (C) 2017 Elsevier Ltd. All rights reserved.