One problem related to engine rattling and whining sounds has been reported for the 2004 Infiniti G35. The most recently reported issues are listed below.
I purchased a 2004 Infiniti G35 in 2008. It all started after an oil change that I received in 2009 less than a month and a half later about 2000 miles of driving looking at my odometer. I heard a rattling noise coming from the engine, and while I was slowing down to come to a complete stop I notice the oil light flicker. I quickly pulled over and checked the oil dip stick, and to my surprise I showed that the low was very low, so I added 4 quarts to the engine. When I got home I checked the drive way to see if there were any oil spots in where I park my car, and there wasn't any oil on the ground. This situation of adding oil at about 2000 mile had went on for my next two oil changes. After which the problem has gotten worse to the point that I am now adding 4 quarts of oil every 1500 miles since the beginning of 2010. Nothing has been done to correct the failure at this time seeing as how I have 108k, and the warranty has expired. After doing some research on the problem it seems as though its a common issue with the G35, and that Infiniti is reluctant in correct or admitting to the problem.