A method for recovering base oil from waste lubricating oil by separating base oil range constituents from a waste lubricating oil mixture, thereafter separating higher quality base oil constituents and lower quality base oil constituents from the base oil recovered from the waste lubricating oil mixture and thereafter treating the lower quality base oil constituents to produce marketable base oil. The total base oil produced from a waste lubricating oil mixture by this process is greater than the quantity producible by previous processes using only base oil separation from the waste lubricating oil mixture or processes which use only treatment of the base oil recovered from the waste lubricating oil mixture to produce the product base oil.

A method for recovering base oil from waste lubricating oil by separating base oil range constituents from a waste lubricating oil mixture, thereafter separating higher quality base oil constituents and lower quality base oil constituents from the base oil recovered from the waste lubricating oil mixture and thereafter treating the lower quality base oil constituents to produce marketable base oil. The total base oil produced from a waste lubricating oil mixture by this process is greater than the quantity producible by previous processes using only base oil separation from the waste lubricating oil mixture or processes which use only treatment of the base oil recovered from the waste lubricating oil mixture to produce the product base oil.

The invention provides a method of desulfurizing an oil composition, the method comprising: flowing an oil composition comprising sulfur through a conduit comprising a constricted region, wherein oil-phase bubbles form in the constricted region and collapse in a turbulent zone downstream of the constricted region; contacting the oil composition with an immiscible deep eutectic solvent in the turbulent zone, thereby extracting at least a portion of the sulfur from the oil composition into association with the deep eutectic solvent; and separating the deep eutectic solvent and the extracted sulfur from the desulfurized oil composition.

The invention provides a method of desulfurizing an oil composition, the method comprising: flowing an oil composition comprising sulfur through a conduit comprising a constricted region, wherein oil-phase bubbles form in the constricted region and collapse in a turbulent zone downstream of the constricted region; contacting the oil composition with an immiscible deep eutectic solvent in the turbulent zone, thereby extracting at least a portion of the sulfur from the oil composition into association with the deep eutectic solvent; and separating the deep eutectic solvent and the extracted sulfur from the desulfurized oil composition.

A method for recovering synthetic oils from a feed stream, the method comprising separating at least a portion of the non-synthetic oil constituents from a commingled stream to produce a partially purified synthetic oil stream and one or more contaminant streams. Extracting at least a portion of the synthetic oil from the partially purified synthetic oil stream to produce a synthetic oil stream and a second contaminant stream.

A method for recovering synthetic oils from a feed stream, the method comprising separating at least a portion of the non-synthetic oil constituents from a commingled stream to produce a partially purified synthetic oil stream and one or more contaminant streams. Extracting at least a portion of the synthetic oil from the partially purified synthetic oil stream to produce a synthetic oil stream and a second contaminant stream.

A method for recovering synthetic oils from a feed stream, the method comprising separating at least a portion of the non-synthetic oil constituents from a commingled stream to produce a partially purified synthetic oil stream and one or more contaminant streams. Extracting at least a portion of the synthetic oil from the partially purified synthetic oil stream to produce a synthetic oil stream and a second contaminant stream.

A method for recovering synthetic oils from a feed stream, the method comprising separating at least a portion of the non-synthetic oil constituents from a commingled stream to produce a partially purified synthetic oil stream and one or more contaminant streams. Extracting at least a portion of the synthetic oil from the partially purified synthetic oil stream to produce a synthetic oil stream and a second contaminant stream.

A method for producing ILSAC GF5 or higher compatible oils from used oil, comprising separating material having a boiling point less than about 350 F. from recovered oil to produce de-volatized fraction and light oil fraction. Separating material with a boiling point greater than about 350 F. and less than about 650 F. from the de-volatized oil fraction to produce fuel oil fraction and heavy oil fraction. Separating material with a boiling point greater than about 1200 F. from the heavy oil fraction to produce partially purified oil fraction and residual fraction. Treating the partially purified oil fraction to separate it into purified oil fraction and contaminant fraction. Hydrogenating the contaminant fraction to remove predetermined compounds, further saturating the fraction and thereby creating a saturated oil fraction. Fractionating the saturated oil stream to produce one or more of naphtha fraction, diesel oil fraction and base oil fraction.

A method for producing ILSAC GF5 or higher compatible oils from used oil, comprising separating material having a boiling point less than about 350 F. from recovered oil to produce de-volatized fraction and light oil fraction. Separating material with a boiling point greater than about 350 F. and less than about 650 F. from the de-volatized oil fraction to produce fuel oil fraction and heavy oil fraction. Separating material with a boiling point greater than about 1200 F. from the heavy oil fraction to produce partially purified oil fraction and residual fraction. Treating the partially purified oil fraction to separate it into purified oil fraction and contaminant fraction. Hydrogenating the contaminant fraction to remove predetermined compounds, further saturating the fraction and thereby creating a saturated oil fraction. Fractionating the saturated oil stream to produce one or more of naphtha fraction, diesel oil fraction and base oil fraction.