I have old gm 5.3 with 225k miles. Good oil pressure. I’ve owned it since new always change oil 3-4k miles. Recently in the last 6 months of so I have heard a noise that sounds to come from the top of the motor like a valve or lifter noise. It happened a few weeks ago and again this morning. I googled and saw some say don’t screw with it as its just noise and nothing will happen. Some say to tear it apart. Others say to do an engine flush. Anyone have any experience with this issue? Seems to be a popular one. Thanks Chad