This study looked into the co-pyrolysis of linseed and polypropylene to produce pyrolysis oil as a fossil fuel substitute for IC engines. The outcomes showed positive synergistic benefits on oil yield from co-pyrolysis as compared to the pyrolysis of individual components. Initially, the study investigated the effect on polypropylene during co-pyrolysis with linseed at temperatures between 350 degrees C and 650 degrees C under different blend ratios. The maximum oil yields for the pyrolysis of linseed and polypropylene obtained were 61.1 wt% and 73.6 wt%, respectively, whereas the maximum positive synergy on oil yield was 6.2 % at 2:3 blend ratio. Fourier transform infrared spectroscopy (FT-IR), gas chromatography mass spectrometry (GC-MS), and physical characteristics were used to further evaluate the pyrolysis oil produced at maximum synergy. It was found that the oil had a higher calorific value of 43.09 MJ/kg, which was fairly close to fossil diesel. For engine analysis, eight different blends containing pyrolysis oil and graphene oxide (GO) nanoparticles were prepared and named PyroD20 (20 % co-pyrolysis oil + 80 % diesel), PyroD40, PyroD50, PyroD20@20 (PyroD20 + 20 ppm GO), PyroD20@40, PyroD20@60, PyroD20@80, and PyroD20@100. After that, an engine test was conducted on the blended fuels to compare them to the baseline diesel fuel (D). At maximum load, the brake thermal efficiency (BTE) for PyroD20 and PyroD20@60 was found to be 37.2 % and 37.8 %, respectively, which was 6.0 % and 7.8 % higher than those of D. The brake-specific fuel consumption (BSFC) for PyroD20 and PyroD20@60 was reduced by up to 22.0 % and 22.7 %, respectively, compared to D. With the use of PyroD20@60, the emissions of carbon monoxide (CO), hydrocarbon (HC), and smoke were reduced by up to 27.0 %, 7.3 %, and 21.2 %, respectively. The produced renewable liquid oil may certainly be used in blends with conventional diesel for IC engine operation.