Systems and methods are provided for modifying or selecting processing conditions for bright stock formation based on compositional characterization of the feedstock and/or bright stock products. In some aspects, the compositional information can include Z-class characterization of the components of a feed and/or bright stock product, optionally in combination with carbon number and/or molecular weight for the components. The compositional information can be used to select processing conditions to allow for removal and/or modification of selected components within a bright stock in order to improve throughput and/or provide desirable cold flow properties.