My feeling is that you should try either Ecocolors dark ash brown or Ecocolors Black. This formulation. however will not make the grays too much lighter than the rest of your hair. You could try medium ash brown for a more highlighted look, but you might still have a slight amount of red in your dark brown hair. It''s hard to say with out seeing your hair and knowing your natural undertones. ALWAYS do a strand test before applying any new color formulation to your entire head. Always use full strength at the new ggrowth and dilute the remaining color mixture by half with water to apply to previously colored ends.