Originally Posted by hallstevenson
After 2007, which has the VQ35HR or VQ37HHR, oil consumption is a non-issue. In fact, the myth about these cars using excessive oil is restricted to the "RevUp" version of the VQ35DE engine, if I'm not mistaken, but it keeps repeated (wrongly) over and over as gospel.
It's not necessarily an issue before 2007 either. I've had two VQs, one in a 2003 G35 and the other a 2004 Quest that I still own at 192k miles. The 2003 (in a G35) never consumed any measurable amount. My 2004 Quest (192k miles) will occasionally consume about 1/4 quart if it's taken on long trips in a 5,000 mile OCI. Pretty negligible.
As stated by The Critic, these are pretty solid engines, although previous maintenance always plays a factor. The rear oil galley gasket is kind of a pain, but mine was transverse mounted in the Quest when I replaced it. Laborious, but not terribly difficult to replace. I'm sure it'd be easier in a rear wheel drive G37. Hook up a mechanical oil pressure gauge to see if it's leaking and bleeding off pressure.