I've always run Pennzoil Conventional 5w20 in my scion with fram tough guard filters (did use a Bosch once) but my last oil change I tryed Pennzoil Platinum 0w20 and a Purolator Classic. Its always run quiet, even on the PP with the only noise being heard with the hood up being the injectors ticking away. I started it up this past sunday, about 1,030miles on the current run of PP and it had a pretty loud valve tap that wouldn't go away even when hot, actually seemed worse the hotter it got. I changed oil again and went back to Pennzoil Conventional and a fram tough gaurd filter just to see if by dumb luck that fixed it, but ofcourse it didn't. Its hard to tell if its coming from the valves, which are cam on bucket I think, so there would be no adjuster to back off. I figure maybe it could also be coming from the cam phasers or maybe the timing chain, but I think that would cause a littelbit different noise than what I'm hearing. I know some ford v8's have the issues with a tapping sound and it comes from the cam phasers, so I'm hopping thats all it is. My questions are, do the 2AZFE's definately use cam phasers, and would warranty cover this since i'm the second owner (only 23,000 miles)? Thanks