my brothers high mileage nissan P/U (over 200K) develops a tick a few thou after an oil change. change it, whatever brand, doesn't matter, ticking goes away. only difference was once, I switched him to amsoil, when the ticking came back, it was LOUD. so loud he freaked and changed it out after only a couple thou.
next step w/ his truck is a auto rx run.
I had an intermittent tick in my MPV, typical for the mazda JE motor. any oil, didn't matter. but, I'm more than 1200miles into a auto rx treatment right now and it's quiet, REAL quiet.