Just changed the valve cover gasket on my 2007 Mazda 6 2.3L. Car has 115k miles and I've been running 5w-30 since day 1. Engine has seen a mixture of Pennzoil Platinum, Pennzoil Ultra and Mobil 1 since new. Pretty happy with the results. Enjoy
Your oil choice and oil OCI have worked well for you. Cam Lobes look good and the internals are clean. I have had similar results with Pennzoil Synthetics.