speedtc,
I have a VQ-30 in my '97 Mazima. I ran Mobil 1 5w30 twice for about 4800 miles each time before getting UOA's. Both UOA's showed very elevated lead, and elevated iron. Other wear metals were normal. No fuel dilution, no AF, low solubles, etc. Just the spiked lead (up to 60 I think), and iron in the 20's. This was at about 78,000 miles (now at 109,000), and I have since ditched the Mobil 1 in favor of Castrol GTX with 3000 mile OCI's. I haven't gotten a UOA since, but I can honestly say my engine was louder with the Mobil 1 5w30 than with GTX. I have just changed with some GC (green), and will do a UOA at 3000 miles with it. I can easily tell my engine is quieter and smoother, to the point that I almost cranked it while waiting at a light (thank *** for tachs. If I hadn't looked at it, I would have cranked away). Anyways, rumor has it the VQ's like thicker oils. Mobil 1 5w30 is well-known to be very thin for 30 wt. And GC is a thick 30 wt. This could explain my observation, and also elevated bearing wear with Mobil 1.
On a related note, have you seen the European viscosity chart for the '97 Nissan Maxima sold in Europe? I had pasted a link to it in a thread in this forum here:
http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=51;t=000692;p=2 Much different than my US copy which recommends 5w30 all year round. This seems to further validate the point that the VQ likes thicker oils.
Depending on my upcoming UOA with GC, I am inclined to try a 15w40 next run, as my ambient temps in Louisiana run from about 25*F (couple days per winter) to over 100*F (almost 4 weeks straight last summer).
Just some food for thought with your VQ.
Dave