Pour 2 cups linseed oil into a pot and place it on the stove to boil. Allow it to cool; add 1 cup of white distilled vinegar and stir.
Lay your leather jacket out on a work surface. Dip a soft cloth in the mixture.
Rub down the entire jacket with the soft cloth, re-dipping it into the mixture as needed. Allow the mixture to soak into the jacket for at least two minutes before wiping off any excess with a clean, soft cloth. This will cleanse and condition the jacket, giving it a fresh new look.
Place a quarter or silver-dollar sized amount of leather conditioner on a soft cloth. Distribute the conditioner evenly around the jacket.
Work the conditioner into the jacket with the cloth. Allow the conditioner to soak into the leather for 20 minutes, then wipe off the excess. Repeat this two or three times.