From what I know can be VANOS rattle, chain tensioner inside engine, or AC compressor belt tensioner pulley or/and tensioner (easiest to fix).
Not sure about AC clutch. Try to on /off AC an listen if it changes. USE different oil may calm down a bit VANOS rattle if it the case. Chain tensioner may diagnose very good mechanic I guess.
Last edited by LX-biker; 07-01-2012 at 07:28 PM.