This invention relates to a method for upgrading petroleum streams which have been treated with peroxide, extracted to remove oxidized sulfur and nitrogen compounds, dewaxed and hydrofinished. More particularly, peroxides are generated in-situ by combining the petroleum stream with a high neutralization number (HNN) crude and adding an oxygen-containing stream. Alternatively, the oxidation of sulfur and nitrogen compounds may be accomplished by adding peroxides in the presence of oil soluble metal catalysts. The peroxides oxidize nitrogen and sulfur compounds in the petroleum stream to more polar compounds which are solvent extracted.