Grohl says he'll start his day with six cups of coffee and is hopelessly addicted to the stuff, and he won't be quitting anytime soon. According to Rolling Stone Grohl tried switching to decaf because of caffeine induced chest pains, but says after a week he "came to the conclusion that decaf blows."
In the same interview Dave Grohl he talked about his on and off again cigarette habit, the fact that he has never used cocaine and many other interesting topics. You can read it HERE