I haven't written on this particular section of NICO before. There are a few things on the VQ Im sure you may want to know. If you already do, then disregard this information, but this is good information.
1) If your VQ is losing/burning oil, it is NOT because of the viscosity. The problem lies in the taper of the cylander bore. All VQ engines have a tappered bore, and on some, it is excessive, to the point where the secondary rings and oil control rings are not making full contact with the cylander walls. Durring heavy deceleration, or high rpm deceleration, the vaccum in the cylander draws oil past these rings. In a situation where you are losing 1qt every 1000 miles, you can be sure to find secondary rings that show minimal signs of wear. (since they are not in contact with the walls, why would they wear?)
2) Got a buzzing/whinning noise when you start the engine? Does it continue durring driving? While a rattling noise durring crank up is more than likely due to low oil, a buzzing or whinning noise while driving MAY BE CAUSED by worn secondary timing chain tensioners. What happens is the plastic guide on the tensioner wears down to the tensioner piston. The chain then rides this piston instead of the guide, causing a whinning noise. In some cases, a bad alternator clutch (yes, the new alternators have clutches) can cause this. In the situation that your tensioners are to blame, expect to spend from $1000 to $1500 to have them replaced and should include new upper (secondary) timing chains.
3) Yet another buzzing, rattling or whinning noise. If you own a Quest van, Maxima, Altima 3.5 and some Z/G/FX vehicles, and get a loud buzzing noise on start up, or rattle, this may be due to the main chain guide breaking. The main guide recieves pressure from the main timing chain tensioner. At the top of this guide, where the chain exits on its way to bank 1 (Left hand from front), the guide wears and eventually breaks at that mounting point. The plastic on the guide then drops about 1/2 inch to reveal some of the metal bracket of the guide. This is the sawing, buzzing rattling noise you hear. Again, it may just be low oil, but if that doesnt fix it, this is probably what you have.
4) VQ wont start, wont spin over or even act like its alive. In some cases, I have found that one of the connectors going into the IPDM board are loose. This is the black box with fuses in it near the alternator on FWD vehicles and near the battery on RWD vehicles. Before you freak out, and after you have tried a jump box, try pressing all the connections into the IPDM to seat them. If it still doesnt start, check to make sure your security light is not on when you turn the key. If your key is turned to start, but the light is on, you have a NATS malfunction, and you should have your car towed to the dealership.
5) Rattling, grinding noise at idle from RWD 6 speed transmissions. GET USED TO IT. They all do it. May not be as loud on some, but they do. My 6 speed is loud, and it is from a 2006 350Z which had less than 6K miles on it when it was removed. I have rebuilt several of these transmissions and see no signs of wear that would be the direct cause of this sound.
I guess thats all I can think of at this moment that could be very beneficial. If your wondering how I came across this information, its from experience. I have been working for Infiniti/Nissan for almost 10 years now. I am a lead technician at a Nissan dealership and have inspected/rebuilt, modified my fare share of VQ engines. Want to see something I've built for proof? Check out my thread on here
I hope this information helps everyone!!!! Feel free to ask questions, but I will say, Im pretty busy most of the time, so it might take a bit for me to get back to you.