NOVELTY - Isomerizing and/or dewaxing (M1) a diesel fuel involves: mixing a biocomponent feed portion (at least 25 wt.% of the combined feedstock) with a mineral feed portion to form a combined feedstock, where the combined feedstock has a sulfur content of less than 500 wppm; and contacting the combined feedstock with an isomerization/dewaxing catalyst under effective isomerization and/or dewaxing conditions including a temperature of at least 350 degrees C.    USE - For isomerizing and/or dewaxing a diesel fuel (claimed); for making winter diesel which is used during warmer months for additional production of biodiesel.    ADVANTAGE - The method produces diesel fuel with improved cold flow properties to facilitate the use in commercial fuel supply; produces winter diesel which is used during warmer months for additional production of biodiesel by increasing refinery utilization. The catalytic dewaxing process can remove oxygen in the biocomponent portion of the feedstock. The dewaxing process can also improve at least one cold flow property of the feed, such as pour point and cloud point.    DETAILED DESCRIPTION - Isomerizing and/or dewaxing (M1) a diesel fuel involves: mixing a biocomponent feed portion (at least 25 wt.% of the combined feedstock) with a mineral feed portion to form a combined feedstock, where the combined feedstock has a sulfur content of less than 500 wppm; and contacting the combined feedstock with an isomerization/dewaxing catalyst under effective isomerization and/or dewaxing conditions including a temperature of at least 350 degrees C, where the isomerization/dewaxing catalyst comprises ZSM-48 and Pt and/or Pd (at least 0.5 wt.%), and the ZSM-48 has a silica to alumina ratio of less than or equal to 75:1. The isomerization and/or dewaxing conditions are sufficient to produce an isomerized and/or dewaxed product having a cloud point of less than or equal to -20. The biocomponent feed portion is hydrotreated prior to contacting the combined feedstock with the isomerization/dewaxing catalyst. An INDEPENDENT CLAIM is included for isomerizing and/or dewaxing (M2) a diesel fuel involving: hydrotreating a feedstock, including a biocomponent portion (at least 25 wt.% of the feedstock), under effective hydrotreating conditions, where the biocomponent portion has an oxygen content of at least 8 wt.% prior to hydrotreatment; and contacting the hydrotreated feedstock with an isomerization/dewaxing catalyst under effective isomerization and/or dewaxing conditions including a temperature of at least 370 degrees C, where the isomerization/dewaxing catalyst comprises a molecular sieve selected from Beta, USY, ZSM-5, ZSM-35, ZSM-23 and/or ZSM-48, and includes hydrogenation metal (at least 2 wt.%) being a combination of Ni and at least one of W and Mo. The isomerization/dewaxing conditions are effective to produce an isomerized and/or dewaxed product having a cloud point of less than or equal to -20 degrees C.