Just a few comments, got my 6mt, new 4/2008.

I have had no issues with the 2008 6mt (although i dont drive it that much, highway business trips). From the start, i decided to use amsoil "SAE 5W-30 Signature Series 100% Synthetic Motor Oil". At first say till about 30k we used some oil and it had to be added, now at 41k there is no oil usage, the oil never moves on the stick. Forced to run 10% ethanol gas @ 93

I can tell the oil needs to be changed by how it starts.

Cold starts with new oil have zero tap sound at all. Oil at 3k has a very very slight tap at start. oil at 4k tap lasts slightly longer (then i change). This "tap" does not sound alarming, im sure the oil need to pump up and with out a "preoiler" its going to make a noise with no oil right at crank.

New oil seems to "stick" to the metal, thus no tap at start, even when cold Older oil does "stick" but not as well.

It also seems to "idle" at a higher "rpm" longer (on start) with oil oil, as if the "computer" can detect some type of drag. new oil low drag, initial start high rpm comes down faster.. i dunno it seems that way i should time it some day (my mustang was like that too, my s10 truck is not) . .

Although the oil still looks somewhat clean @ 4k as that i can see it thru the stick no problem, it seems to me, although its "synthetic" there is micro contamination that thickens the oil (vvl helps make the oil dirty faster). They say 15k per change with amsoil, i say that's impossible, it would be like mud...

I am in NJ. Summer time oil "wears" out faster than in winter, which makes sense.. ( If i could "super" filter the oil, i bet the oil still would be fine). My thinking is, i could be wrong, this engine goes through more "stress" than other engines as that the vvl varies compression ratio, so the rings are under ever changing compression ratios and overall deals with more varying pressures then just a normal cam based engine. That means the oil needs to deal with more, thus wears out quick, no matter what oil you use.

So although costly, oil changes every 3k-4k and of course filter.

Based on the oil plug looks, the oil filter adapter and oil stick, the engine is seems to be staying crystal clean. (which for this engine, any "build" up with throw off the internal workings of this engine, it works at extreme tolerances)

at 30k (2012) had the rear, transmission oil changes. Brake fluid and cooling flushed (computer was "flashed and updated"). Apparently emergency brake cable needed to be replaced.. i have K&N air filters so i just clean them when needed.

I don't beat on it too much, but a few "powershifting" events have occurred (sure is smooth if you go fast), along with a few roll-ons with other g35-37's. Brakes still seem OK

so thus far no issues in which it had to goto the shop at all.

On a side note, I can get over 30mpg if you find a bus or van ; you can "draft".

Sometimes with buses if you can get in the "sweet" spot it almost pulls you, but kinda too close..

 

Amsoil is great oil. I've run it for up to 19k miles in my G35 coupe with zero issues. VVEL actually varies the valve lift continuously on the intake side. It doesn't actually vary the compression ratio. At low throttle position, the intake valves open only slightly. Push down on the throttle, the intake valves open more and for a longer duration.

There's a great in-depth technical article on the VQ37VHR and it's VVEL system. Click on the engine link at 370z.com > Home

 

lol at draft equal rock chips front bumper...

 

But hey you can afford to touch up the chips from the gas mileage savings... JK +1 for mud flaps