Deasphalted residual oil (DAO) and the aromatics-rich extract that is derived from DAO have low polycyclic aromatics contents, relatively low aniline points, and high flash points. They form blending stocks that improve properties of mixed feedstocks to consistently produce environmentally qualified rubber processing oil (RPO) by extraction under low solvent-to-oil ratios and moderate extraction temperatures. Distilling a petroleum crude oil under atmospheric pressure generates a bottom residual oil which is then subject to vacuum distillation to yield a bottom residual oil. DAO is produced by removing the asphalt from the vacuum bottom residual oil through extraction with light paraffinic solvent. The extract of DAO is a co-product in the production of the bright stock of the lubricating oil through extraction. The feedstock is mixed with the extract from a petroleum fraction boiling in lube oil range. Liquid-liquid counter-current extraction yields a raffinate stream; removal of solvent therefrom produces the RPO.