Used lubricating oil has been the subject of much debate over recent years in Ethiopia. The amount ofrnlubricating oils disposed annually in the country is considerably large. This amount of waste lubricatingrnoil has a significant impact on both economic and environmental aspects. In this research Acid-clayrntechnology has been tested for re-refining used lubricating oils, usually Total Rubia Tir 7400 15W-40rnand Total Quartz 5000 20W-50 by varying acid ratio between 10-20% and adsorbent ratio between 15-rn25%. The result showed that the efficiency of the recycling operation depends on these two reagentrnratios. Increasing the acid concentration showed a significant difference over the yield, kinematicrnviscosity and other physicochemical properties, however increasing the amount of acid over thernoptimum point made no significant change. Better bleaching and yield and other physicochemicalrnproperties were achieved with increasing adsorbent ratio. A maximum yield of 71.45% was obtained forrnRubia Tir 7400 15W-40 at acid ratio of 15% and 25% adsorbent. Whereas a minimum yield is obtainedrn42.6% at acid ratio of 10% and 15% adsorbent ratio. For Quartz 5000-20W-50 a maximum andrnminimum yield, and other physicochemical properties were obtained at 15:25 and 10:15 acid adsorbentrnratio respectively with72.5% and 49% yield. All metal contaminants are substantially removed; totalrnbase number is enhanced while carbon residue is significantly reduced for both lubricants suggesting thernmethod works effectively regardless of the lubricant type.