Re-Refined Waste Oils Slicker Recycling, a waste oil collection company, uses Hydrodec's hydrogenation refining technology to re-refine used and contaminated waste oil. This company applies proprietary technology to re-refine used and contaminated waste oil to produce high-quality industrial oils for reuse., The results presented that all synthesised Gemini surfactants from different waste oils including waste palm oil, waste rice bran oil and waste rapeseed oil showed similar trends which an increase in surfactant concentration led to a decrease in surface tensions up to a certain limit [109]., Re-refined base oils are revolutionizing the lubricant industry by enabling a circular economy that reduces waste, conserves resources, and minimizes environmental impact. This comprehensive article explores the re-refining process, highlighting its energy efficiency, environmental benefits, and performance standards., Some authors have shown that re-refining used oil using a combination of solvent processes and hydro-processing can produce a high-quality base oil (Sarkar et al., 2023). , The company found that lubricants using rerefined base oil saved 7,500 metric tons of greenhouse gases for every 3.78 million liters used. Safety-Kleen collects more than 757 million liters per year of waste oil and is the largest rerefiner in North America., Abstract Used oil recycling technology has undergone significant changes over the past decade. With the newly developed re-refining technologies it is possi-ble to produce higher quality base oil compared with the traditional and old acid clay methods. Among other methods used are: solvent extraction (N-methyl-2-pyrrolidone, interline process, combined vacuum distillation and solvent extrac .