I just groom mine everyday. And before shows I put show sheen on her. But don't put show sheen where the saddle goes. It can rub hair off a horse. Put the saddle on first then show sheen....thats what I do
Flaxseed works great.. and I also will feed veggie oil. I like EQ Solutions as a shampoo... you spray it on leave it for 5 minutes (I like to curry it in too) rince it off.. and they spray it back on and leave it... leaves them super shiny.
I look for oils that are higher in omega 3.....flax and canola are good sources and fish is best. Most horses get plenty of omega 6 in their feed and benefit from the added omega 3. Omega 3 has anti-inflammatory properties at the proper ratio to omega 6, while on the flip side omega 6 can cause inflammation if you get beyond the 10:1 ratio (omega 6 : omega 3).
Thus far no studies have shown that you can give too much omega 3.