Abstract: A process for creating higher quality and lower quality base oils from used lubricating oils and crude oils, wherein the higher quality base oils may be either Group III or Group II and the lower quality base oils may be either Group II or Group I. Vacuum gas oils produced from used lubricating oils and from crude oils are processed via two or more process steps, including solvent extraction, solvent or catalytic or iso dewaxing, and hydrotreating. Such process enables efficient conversion and operation of refineries formerly capable only of making Group I base oils, even as their ability to make heavier base oils, waxes, and bright stocks is preserved, substantially to the same extent as such products had been made prior to undertaking the conversion.