Mix a solution of one part vinegar and two parts linseed oil in a bottle.
Shake the solution vigorously until the linseed oil and vinegar are thoroughly mixed.
Moisten a soft cloth --- a chamois or old cotton T-shirt --- with the linseed oil solution.
Rub the linseed oil into the leather, using circular motions. Coat all of the leather. Shake and reapply the linseed oil to the cloth as necessary.
Leave the linseed oil to sit on the leather for 10 minutes.
Rub the leather in circular motions with a dry, clean cloth to buff and shine the surface.