Diethyl ether is an oxygenate chemical/hydrocarbon (HC) that can be used as a fuel additive to enhance fuel reactivity. Due to its high volatility and low auto-ignition temperature, it has paved the way in enhancing direct-injected fuel combustion efficiency. The study employed the use of binary blends of watermelon seed oil (WSO) and pine oil (PO) doped with diethyl ether (DEE) as a fuel additive for the first time. The binary fuel samples were prepared by mixing WSO with PO in volumetric ratios of 30:70, 50:50, and 70:30 respectively. DEE was added to the binary blend in the volumetric ratio of 10%. The study was conducted in a four-stroke single-cylinder engine which was operated at four different load conditions with constant speed. The first and second laws were analyzed using the acquired data from the computerized engine system. The results of the experiment demonstrate that the use of a blend of PO and WSO raises the sustainability, energy, and efficiency indexes. Blending PO reduces brake-specific emissions, like carbon monoxide (CO), soot, and HC emissions, but it also increases NO and CO2 emissions in the exhaust. Nitric oxide emissions, therefore, rise in tandem with increases in energy and exertion efficiency. The database information can be used as a reference for assisting the automotive and biodiesel industries in effectively capitalizing on the utilization of alcohol (OH) as a fossil diesel replacement.