I had to chime in on this one...
I have been the owner of 2 QR25DE motors. The first gen QR in my '03 Altima gave up the ghost when the catalytic converter failed at 80,000km. For those who don't know, the catalyst on the early Sentra's/Altima's have been known to overheat, breakdown the ceramic substrate which then gets sucked back into the motor scoring the cylinder walls. Oil consumption then goes through the roof. The QR does not have an EGR system, it uses variable valve timing to change the valve overlap and take advantage of exhaust gas reversion. Anyway, the motor was replaced and ECU updated and it held up for over 150,000km when I sold it. I ran both M1 5w30 and GC in this motor with 10,000km OCI's. I could scarcely tell the difference in fuel economy, but the motor did seem to run quiter with the GC. I never had oil consumption issues in the replacement motor.
My second QR25DE is in the Rogue, same as Pesca. The 2nd gen motor does have some changes including an increase in compression, revised balance shaft location, single path intake (no more double intake runner and butterfly valves), a new upper engine mount, and I'm sure a host of other small technical changes. The bore, stroke, rod length, cam shaft, bearing journals, etc seem to be unchanged... at least this is what a comparision of the FSM's (03 Alty and '08 Rogue) tell me. From the outset, this motor is far smoother and quieter than the 1st gen QR. It's still somewhat noisy when cold but it does quiet down once warmed up. This seems to be characteristic in these motors. I'm on the 1st oil change with GC and a WIX filter at 12,000km. No oil burning issues. I average 8.3l/100km or 28mpg in a mix of hwy(70%) and city (30%). No UOA so far, but I intend on getting one done on my 2nd oil change. I will continue with the GC for now unless the UOA tells me otherwise.
