Some people believe that Bennington used auto tune because they feel that his voice sounded too perfect in some of his songs. They argue that it is impossible for a singer to sound so consistently perfect without the help of auto tune. Others argue that Bennington was simply a very talented singer and that he did not need auto tune to sound good.
There is no way to know for sure whether or not Bennington used auto tune. However, it is important to note that there is no evidence to suggest that he did. It is possible that he did use it on occasion, but it is also possible that he did not. Ultimately, it is up to each individual to decide whether or not they believe that Bennington used auto tune.