Hey,
First of all I never owned a G35, but I am sure most of you know how to turn a Spanner and are a little bit familiar with it's beastly v6 engine.
I own a renault vel satis here in Germany, this car was built 2003, it has the exact engine Block as the 350z, since this engine isn't known here in Germany I'm kinda lost, I even have difficulty buying spark plugs here .
Now the serious stuff, my car has a 100,000 original km's and lately has been consuming lots of oil, I would say half the dipstick measuring Portion for a 300km drive. Intake manifold right before the Plenum is full of fresh clear oil. I checked compression right away and all 6 cylinders have between 165-175 psi ( I could not confirm hot pressure testing because it was not easy removing the plenum to test so the engine was cooled off by then ) and please excuse my metric System. I checked the pcv valve and there's a free Ball in it which I could hear it moving with the slightest move. Now, why could this Motor be burning so much oil with this compression? Is it a Design fault, do I maybe need new rings? I use oil weight sae 5w40. I really pamper my car and never abuse the engine. Any suggestions what could be the culprit here?
the car also smokes when applying WOT, it doesnt smoke when cold started though so I think valve seals are doing just fine.

Stilkus,

It sounds like valve seals to me. Just because you're not seeing smoke when cold doesn't mean they aren't leaking. There are few ways for oil to get into the intake except for it blowing by the seals. Now, I'm not specifically familiar with the peculiarities of this engine so I'm just going by several decades of general knowledge and since there generally aren't oil paths in the intake plenum then the seals are the likely culprit. You could have bad oil rings though and still have good compression, but with oil in the intake I doubt that is the cause.