An improved slurry catalyst feed system for heavy oil upgraded is provided. The catalyst feed system comprises a fresh slurry catalyst and a deoiled spent catalyst, with the deoiled spent catalyst being present in an amount of at least 10% the catalyst feed system. The deoiled spent catalyst is a slurry catalyst that has been used in a hydroprocessing operation resulting in than 80% but more than 10% of original catalytic activity, and containing less than 10 wt. % soluble hydrocarbons as unconverted heavy oil feed. The deoiled spent catalyst is slurried in a hydrocarbon medium as dispersed particles prior to being fed to the heavy oil upgrade system.