I'm beginning to think that this is simply an unavoidable side-effect of the robust timing chains Nissan/Infiniti use in their engines. I love the performance of my VQ35-powered G35, but under the right conditions, it generates terrible timing chain rattle. There's a TSB out on earlier-build VQs that seems to ascribe the sound I have to the variable valve sprokets. The sound, however, is unmistakably a chain sound. It's hard to put into words, but I can say that if you hear this sound come from the engine, there's only one thing on earth that could make such a sound -- a semi-taut chain being dragged across a hard surface.
I've experimented with a couple different oils and both the tall and short oil filter design. I get the sound only on start-ups, so I've looked at things that might impact oil flow and the amount of time it takes to get oil pressure up in the chain tensioner. I thought GC had helped, but at the beginning of my second winter with the car, it rattles with the GC. I just put in some Mobil Clean 5k (ARX rinse oil) and it seemed to quell the rattle, but that only lasted a few days, now the rattle is back. Grrrr. Who knows. . .