A method wherein either crude oil or a used oil lubricant is processed to produce an intermediate lube distillate which is then hydrotreated to produce a hydrotreated base oil which is then processed by solvent treatment to produce a higher viscosity index base oil (such as Groups II+ and/or III) and a lower viscosity index base oil (such as Groups I and/or II), in each case as compared with the viscosity index of the hydrotreated base oil. In the solvent treatment, one or more solvents are utilized to selectively separate higher viscosity index components from lower viscosity index components found in the hydrotreated base oil, and after the separations have occurred, the solvent is preferably recovered for re-use in the process.

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 oil 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 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.