Re: Engine Rattle? ..... 156 2.5 V6
It sounds to me as if it could be a sticking tappet, but I would not rule out a cambelt issue.
It seems strange that the noise has only appeared 14k after the belt change, it could be that the tensioner was not set tight enough, and now the belt has settled there is too much slack in it.
I also had problems with a ticking Twin spark a while ago, it turned out that a spark plug was loose in its hole, the ticking being caused by gas escaping past the threads.
Firstly as you say, try changing the oil, and maybe using some flush first, and see if that helps.
I hope that gives you some things to go on.
Giulietta 2.0JTDm (170), BMW 335i Cabrio