Used Motor Oil Regeneration Efficiency of Type X Fly Ash–Based Zeolite Alone and Combined with Other Adsorbents

This research article assesses the used motor oil’s (UMO) regeneration efficiency of a synthetic type X zeolite (siliceous fly ash–based) alone and combined with other adsorbents (composite adsorbents), namely activated carbon, bentonite, and acid-activated bentonite from Goshica’s (Kosovo) region. The UMO treated with the regenerating mixes has run about 20,000 km. Parameters including density, kinematic viscosity, viscosity index, pour point, and sulfur content were measured in the untreated and treated UMO and compared to those of the reference oil with additives of type SAE 5W-30. All regeneration mixes showed good regeneration efficiency, restoring the UMO’s parameters to almost the original ones of the reference oil with additives (SAE 5W-30). Only the zeolite alone could significantly reduce the sulfur content (removal efficiency 60%). This method deserves further investigation and with some improvements, it can be established as a reliable regeneration method for some UMO.