at anywhere from 25%-60% throttle, if my '03 maxima was between 1700rpm and 2000rpm, it would rattle. after a lot of experimenting, including driving around with the hood up and someone sitting on the engine, I was convinced it was the timing chain making the noise. additionally, on very cold mornings it would rattle for a brief second as the engine was started. the car's got 116k miles on it now, so that's not reaally out of line. since that's a lot of money, i've been putting it off. when it came time to change the oil, i found that I was 1.25 quarts low(very embarrasing to not have checked for the whole 3000 mile interval). since it's so cold out right now, i also switched from 5w-30, to Mobil1 0w-40. it's been two weeks now, and the noise is gone. I can not repeat the problem even on purpose. I do not know if it was all because i was low on oil, or if this motor really likes the new weight, or both. i do know, it idles so quietly now, it's hard to tell the engine is on even if you're standing next to the front tire with your hand on the hood.
hope this helps someone.

 

Now that was funny..

I bet you will be checkin your oil more often...also are you going to still with mobile 1 now?

 

the sound you are hearing is the timing chain...which is a result of your low oil...which is a result of you burning oil.

the timing chain tensioner used oil pressure to stay tight. if your oil is low, the tensioner is lose and you hear the rattle.

here is my whole ordeal
http://forums.maxima.org/showthread....g+chain+rattle
http://forums.maxima.org/showthread....il+consumption

 

My oil level is half-way between L-H and I still get the rattle from 1700 to 2000rpm. I use Mobil 5W30 but am going to try Castro Syntec 0W30 European Blend (or the green gold!). We shall see.

 

that's funnybecuase it was the other way around for me. My chain was rattling like no tommorrow. I was burning 1 litre of oil per 1000km using mobil 1 5w-30 synthetic. Got tired of putting in a litre per week at 10 bucks a shot while waiting for my warranty claim so I switched to 5w30 dino oil. The timing chain stopped rattling immediately. I'm still burning oil at a reduced rate and no timing chain noise.