The need for energy sources is one of the major problems for all countries in the world. Biodiesel is one of the alternative fuels. The use of 5% biodiesel in diesel fuel blend is usual, and most countries have planned to use 20%. Glycerol is a by-product of biodiesel production. Therefore, due to the increase in this substance, glycerol management is substantial. In this study, biodiesel was produced by the transesterification process from waste cooking oil (WCO); then, the triethylene glycol mono-methyl-ether (TGME) as a novel additive obtained from glycerol by the etherification method. The Dual-Fuel Diesel Engine mode (DFM) is one of the most suitable ways of achieving efficient and clean combustion. Dual-fuel combustion has been performed through the use of natural-gas (NG) as the main fuel and diesel/biodiesel blend The DFDEm engine was run under three different high NG ratios (60, 70, and 80%), at full-load and 1500rpm. Biodiesel was used at two levels of 5 and 20 vol%. TGME was added at four levels (0.1, 0.2, 0.3 and 0.4 vol.%) to fuel blends. Results showed that glycerol conversion and recycling into TGME additive is important, because, the presence of oxygen in the chemical structure of the TGME additive can make it a suitable oxygenated additive. The TGME as an oxygenated additive improved the most parameters of the engine. Oxygenated fuels contributed to the combustion process and improved it. The best conditions achieved by adding 0.2 vol% TGME additive into diesel fuel at the DFM engine in NG70 mode, under these conditions in comparison to conventional diesel combustion brake power, and brake thermal efficiency increased by 10.54 and 12.77%, but the generated power cost amount decreased by 20.16%. Also CO, CO₂, and NOx emissions decreased by 76.77, 40.9, 1.31%, respectively.