If you have a rattle, even sporadic, it's time. As I said, mine was so slight (only rattled every 5th start or so) that no one but me could hear it, yet the guide was gone. I pulled what was left of it out of the pickup screen on the new pump, after I finished the job. It ran fine, somehow hadn't jumped time. The chain has started to wear into the case, which I had to replace. If you wait rough idle, codes, etc., that means you're waiting for it to jump time, and you'll be buying a new engine, or pulling your heads to do the rebuild. Mine did the phaser knock for 50k miles also, but the rattle is the key. Thick oil only hides the rattle, it doesn't fix it, and over time only makes the problem worse. The tiny oil passages do not like or want thick oil; valve timing is based on oil pressure,, so thinner oil is needed to get oil where it's supposed to go. Tear it apart; you'll find a tensioner seal blown out, I guarantee it.

 

I hear you - but I've poured my old oil thru a sieve last 3 changes and get no glitter (chain rubbing timing cover) nor teflon pieces...would think those would show up if problem?