Truth in The Tin Drum

I want to point to a few of the major similarities I found between Gabriel Garcia Marquez' 100 Years of Solitude and The Tin Drum by Gunter Grass. In my analysis of the latter I mainly paid attention to the question of Oskar's reliability as a narrator, however, I approached the idea with thought in mind of previous discussions, such as external influences in the writing of a novel-like we see in Marquez' piece-which brings me to the first similarity between the two books. In addition to the Marxist like approach to crafting a story, that is the two authors borrowing tales from history to influence their stories, both employ magical realism to help the progression and belief in their messages as well. This brings me to my main point, which is the methodology employed in the two tales.
 Both authors similarly play with concepts of narration and history, and both in an episodic kind of way. With use of magical realism in 100 Years, we saw how Marquez tried to present his spin on history, and in a way teach a lesson-that history can be forgotten or ignored. He wanted to convey the idea that seemingly impossible events could become believable through detail-as he mentioned with his example of the absurd yet imaginable number of butterflies at one point in the story. But his lesson was more or less a commentary, and not necessarily an argument. Similarly, Grass' whole thing in The Tin Drum is about choice. That is the choice to seek or subscribe to certain truths, and I believe Grass tests this methodology or process of truth-finding by bringing into question the reliability of the narrator.
Throughout the book we follow a picaresque protagonist. The subject of the novel is no matter that can be approached comfortably as well. And while in the beginning we see the main character to hold such concrete ideas about the world and others, he changes by the end and realizes the nature of the human situation, which is dynamism and dealing with present situations-or future ones.
In Grass' nobel lecture and through his own personal philosophy and the way he constructs this novel we see that he believes identity is defined by ones own unique experiences and personal interactions with others and themselves. In a way similar to the ending of 100 Years, Grass sort of addresses the concept of how to approach history, and leaves it up to the reader to believe in his story and message, and follow his journey, which is seemingly uneasy and ever-changing, or to borrow from his nobel lecture "To Be Continued..."
Grass uses the eyes of a struggling Oskar, struggling against shame, innocence, guilt, and truth seeking, as a lens to personify the times he was born into and provoke thought about them.