A process for the production of a distillable hydrocarbon product stream from a first distillate hydrocarbon stream, a second distillate hydrocarbon stream and a waste lubricant stream by means of contacting the waste lubricant stream with a hot hydrogen-rich gaseous stream to increase the temperature of this feed stream and vaporize at least portion of the distillable hydrocarbonaceous compounds thereby producing a distillable hydrocarbonaceous stream which is immediately hydrogenated in an integrated hydrogenation zone. The vaporized waste oil stream is admixed with a first distillate hydrocarbon stream before introduction into the hydrogenation zone. The second distillate hydrocarbon stream is converted in a hydrocracking conversion zone in order to produce lower boiling distillable hydrocarbon products and an aqueous ammonia solution which is admixed with a partially condensed effluent from the hydrogenation zone in order to neutralize at least one acid gas. The resulting admixture is partially condensed to produce a hydrogen-rich gaseous stream and a distillable hydrocarbon product stream.