Recent studies have shown promising performance benefits of pipelined stencil applications. An important factor for the computing efficiency of such pipelines is the granularity of a task. We presents GOPipe, the first granularity-oblivious programming framework for efficient pipelined stencil executions. With GOPipe, programmers no longer need to specify the appropriate task granularity. GOPipe automatically finds it, and schedules tasks of that granularity while observing all inter-task and inter-stage data dependencies. In our experiments on four real-life applications, GOPipe outperforms the state-of-the-art by up to $4.57\times$ with a much better programming productivity.