A non-petroleum or renewable feedstock containing oxygen and contaminants of metals, gums, and resins is treated by introducing the feedstock into a reactor at a flow velocity of at least 20 ft/sec. The feedstock is heated within the reactor and cooled to form a reduced-temperature reactor product. At least a portion of the reduced-temperature reactor product is feed into a hydroprocessing reactor containing a hydroprocessing catalyst to form a hydroprocessed product. The hydroprocessed product is cooled and non-condensable gases, metals and water are separated and removed to form a final product. The final product has an oxygen content that is 60% or less of that of the feedstock, and wherein the final product comprises 25 wt % or less any triglycerides, monoglycerides, diglycerides, free fatty acids, phosphatides, sterols, tocopherols, tocotrienols, or fatty alcohols, from 5 wt % to 30 wt % naphtha, and 50 wt % or more diesel.