I just searched all the threads regarding engine noise and didnt see anything quite like what I have. I started my 2003 G35 coupe A/T a few days ago and a LOUD metallic sound like a fan blade hitting a radiator started. I turned off the engine, checked the oil and it was a little low. Put about a half quart in and the noise was still there but sounded more like rattling valves. Sceduled an appointment for today and when I started it this morning there was no noise at all. Infiniti called and said nothing is wrong. That noise was too loud for everything to be fine. I had a truck once with a bad ring that periodicaly made similar noises. Its got 38K miles on it so its still has plenty of warranty but I am concerned. Any ideas? Noise was like a metallic ticking that sped up with engine RPM. Possibly a sticking valve?