Linseed Oil Bleached is Cold-pressed linseed oil which is then bleached. This medium increases the fluidity of oil colors.  When using this medium, brushstrokes can possibly be removed. It increases the gloss of oil paints but it also lengthens the drying time.  Compared to Linseed Oil, there is less yellowing but it dries much slower.  This can be diluted with turpentine or white spirit.

reference: www.oldholland.com