Very oily hair at the end of the day?

I'm a guy with medium length hair. By the end of the day it droops and shines because of oil. Is there anything i can do to fix this? Right after a shower its awesome- light and fluffy. At the end of a long day, it becomes oily, sticky, and shiny. What can i do to fix this? Is there a certain shampoo i should use? I use Suave 2-in-1 shampoo+conditioner for men (everyday, because otherwise my hair will be even worse). Could this be the problem?