My appy was nearly all white, and I tried everything. The best of the best is Farnum's white n' brite. It's a rich rich purple shampoo that just makes grays glow. My family affectionately calls it "the purple stuff". Just be sure not to leave the shampoo on your horse dry- or it will turn him purple!

For the tail, I tried MTG at the base of the tail, massaged in to encourage growth and kept it detangled using cowboy magic detangler and finger combed (brushing too often breaks the hairs). If you have to brush is, trying washing the tail first, spray on detangler, then start to brush.

Great feed helps manes and tail grow, and a bit of oil with thier dinner ( I use vegetable oil) adds some more gloss. Ask your vet first, though.