Originally Posted By: rcy
The VQ apparently has a problem with the secondary timing chains wearing out the plastic tensioner guide shoes. Any recommendations for an oil that will protect plastic (or I guess help with metal chain rubbing on plastic guide shoes) or is this just a [censored] design flaw, no matter what oil I run.
Thanks.
Between myself and my family, we've had a few VQ-engined vehicles in the stable for many years. Although I no longer have one, I put over 250,000 km on my VQ-powered 2005 Altima over 7 years.
Let me clarify... There are many problems that have been noted with the VQ timing chain setup. The secondary timing chain issue that you're talking about is due to defective chains that have sharp edges (as other posters have already mentioned). If your car had that problem, it would have already come up. If it hasn't yet, then it probably won't (and this particular problem cannot be addressed by oil selection or viscosity selection).
Now, although less common in this engine family, the primary chain can have a multitude of issues depending on how lucky you are. Chain stretch/wear over time is an issue, as well as primary chain guide failures. Also, primary tensioners are known to go bad, become lazy, or have the plastic guide worn off of them so that the actual tensioner plunger (metal cylinder) contacts the chain and wears it out much more quickly. Primary chain problems can manifest themselves by causing a momentary rattle on cold start-up, poor performance due to mildly affected cam timing, or rattle at high RPM due to improper chain tension (caused by failed guides). These are all very difficult to fix in place, and most dealers will pull the engine as it's easier to do it this way. My car had some sort of primary tension issues towards the end, but still ran okay (but with some reduced performance). I suspect that some of the guides were wearing down and were coming up for replacement.
In any case, I believe these primary chain and tensioner issues are caused by many factors, one being oil viscosity, two being oil temperature, and three being cheap parts / poor design. Two of these items are in your control. I typically used a 30 grade synthetic oil for the life of the car (0W30 or 5W30), but that didn't get me anywhere (obviously) since chain issues still crept up on me. A friend of mine uses nothing but 0W40 (either Mobil 1 or Castrol Syntec 0W40) and he does not have any chain problems with his VQ. Mind you, he is not up to the mileage that I had (yet), although he's getting close to 200,000 km already.
My opinion would be to use 0W40, and also add an oil cooler kit (many bolt-on kits available for the VQ) if you want added benefit / protection of cooler oil. The VQ heats oil up very quickly, and runs with hotter oil temperatures than most commuter vehicles (even with a factory equipped oil-coolant heat exchanger). Plus, if you read your owner's manual closely, you will see that Nissan recommends 5W30, 10W30, and 10W40 for VQ engined (up to a certain year before they took that wording out of North American manuals lol). Mine certainly recommended those grades, which means that a 40 grade oil is completely safe and recommended for use by Nissan (in 2005 anyway).
You have nothing to lose
