Everyone has a different opinion on oils, linseed/soya/cod liver...............I've just always fed Tesco's Vegetable Oil, and the majority on my yard do too
Linseed oil is the best one for the job, but veg oil is cheaper and does a good job...you can also feed seaweed for coat condition! I've never had a shiner horse than when I feed him seaweed!!
I have been feeding black sunflower seeds and he is very shiney and his hoof condition has improved no end. He normally has very poor soft hooves that break easily, but even in this awful wet mud filled weather his feet have been exellent