For most of the Epic of Gilgamesh, Gilgamesh and Enkidu go about their business with barely a guide or mentor in sight. True, Gilgamesh talks to his mom Ninsun every now and again, but she's pretty hands-off in her parenting style. Sure enough, without proper adult supervision, Gilgamesh and Enkidu do what pretty much any pair of young hotheads would do, given superhuman strength and endless free time: they get into trouble.
After Enkidu dies, however, Gilgamesh experiences a turnaround: he realizes he needs some guidance. And so, he makes the long journey to speak to the distant, Yoda-like Utanapishtim. And his message isn't really all that surprising: ordinary humans can't achieve immortality, and the only ones who did (Utanapishtim and his wife) did so under very unusual circumstances. (Although, he does mix up his message a bit by caving in to his wife's demand that he let Gilgamesh know about the flower of youth.)
But the issue isn't so much what Gilgamesh knows, but his attitude toward what he knows. At the end of the day, it may be Gilgamesh's arduous journey to and from the realm of Utanapishtim that is his true mentor.