The disposal of waste plastic has intensified into a massive environmental crisis. A sound disposal technology may be extremely expensive or complex in operation. As a result, experts are investigating alternative methods of recycling waste plastic. Waste plastic oils (WPO) are gaining interest as a replacement for petroleum-based fuels since they can deliver substantial performance while having a low environmental impact. The goal of this research is to look into the use of WPO in a retarded timing (RT) engine with a partially stabilized zirconium combustion chamber surface (PSZ). In addition, Exhaust Gas Recirculation (EGR) augmentation was used to realize WPO performance fully. With 20% EGR, the engine's thermal efficiency increased by 6.33%, along with the significant reduction of NOx. However, CO, HC, and smoke particle emissions increased by 4.56%, 5.76%, and 3.54%. More research on the sustainability aspects of the WPO is required before considering it as a fuel for the transportation sector.