Reclaiming used lubricating oil

A process for the production of an essentially pure oil stock from a used lubricating oil containing undesirable components comprising:

• (a) contacting said used lubricating oil with a demetallizing agent to form an oil phase essentially free of metal contaminants;
• (b) contacting the now demetallized oil from step (a) with a relatively small amount of concentrated acid;
• (c) allowing the acid treated oil of (b) to phase separate into an oil phase and an acid phase;
• (d) contacting the resulting oil phase from step (c) with at least one adsorbent selected from the group consisting of activated carbon, silica gel, clay, bauxite and alumina;
• (e) separating the oil and particles from step (d) resulting in a finished clear oil product.

A process for the production of essentially pure oil stock from a used lubricating oil containing undesirable components comprising:

• (a) contacting said used lubricating oil with an aqueous solution of a treating agent capable of reacting with essentially all of the ash-forming metal constituents in said used lubricating oil rendering them removable under conditions sufficient to disperse said agent in said lubricating oil and reacting a sufficient amount of said agent with said metals of said lubricating oil;
• (b) removing a major portion of the water from the mixture resulting from combining said aqueous solution and said lubricating oil;
• (c) separating solids from the oil resulting from step (b) to obtain a demetallized partially purified oil;
• (d) contacting said demetallized partially purified oil of step (c) with a relatively small amount of concentrated sulfuric acid;
• (e) settling the mixture of step (d) to form an oil phase and an acid phase;
• (f) contacting the resulting settled oil from step (e) with at least one adsorbent selected from the group consisting of activated carbon, silica gel, clay, bauxite and alumina;
• (g) separating the oil and the particles from step (f) by filtration resulting in a finished clear product.