This study investigated the impact of the addition of a novel series of biodiesels on diesel engine performance, emissions and combustion characteristics. Two non-edible biodiesels, namely waste cooking oil and macadamia oil (Macadamia integrifolia) biodiesels were experimentally tested in this study. The fuel blends were prepared in such a way that the fuel oxygen remains at 3.35 wt% in the blend. A 4-stroke, 4-cylinder, naturally aspirated diesel engine was used for all experiments. The engine was coupled and loaded with an eddy current dynamometer. The experimental results indicated that compared to diesel, all diesel-biodiesel blends show no significant changes in engine performance, but higher combustion efficiency and significant reductions in all major diesel emissions with a little penalty of NOx emission. Fuel energy and exergys were almost unchanged or slightly lower than diesel. (C) 2019 Elsevier Ltd. All rights reserved.