I'm always trying different shampoos & conditioners & the best combo I've found is MinkSheen & Tomlyn Nova Pearls Creme Rinse Conditioner. It leaves my 4 (I've got 2 that tangles very easily, 1 cotton coat & 1 modified) shiny & silky for days.
Bio-Groom that Nancy recommends are great too, make sure you ask for the Silk Conditioning Creme Rinse.
