This leads to the next issue that has arisen with the VQ37VHR. When the engine was first introduced in the G37, there were complaints about a ticking noise coming from the engine, particularly after the first oil change. As common, particularly in these hard economic times, dealerships sometimes offer promotional oil changes at a very low price to help bring customers in the door. Typically these oil changes are a loss leader promotion where the dealerships might actually lose money just to attract customers. Naturally this results in the car getting the cheapest possible oil in the changes. If a G37 had low quality oil put into it, a customer might notice a very slight ticking noise emanating from the engine later. The noise is so slight that it can usually only be noticed when driving with the window open, close to a reflective surface like a hard wall. More G37 customers complain than 370Z customers probably because the G37 has superior NVH (quietness) to the 370Z and an Infiniti customer is pickier.
It has been determined that the noise is caused in part by not using the super oil. The VQ37VHR engine’s VVEL system uses a reciprocating shoe that wipes back and forth across the cam follower instead of rotating like a cam lobe. This wiping action makes it difficult to establish a hydrodynamic film of oil in the interface between the shoe and the cam follower. Low hydrogen DLC coating is used here to both reduce friction, improve wear in this more difficult to keep lubed interface and to attract the super oil.
The super oil’s attraction to the cam followers helps cushion them hydraulically against the slapping action of the VVEL shoe, thus damping out the noise. Nissan’s TSB for the noise involves switching to the ester super oil and reflashing the engine’s ECU. Nissan has determined that revving the VQ37VHR without load helps contribute to the noise. What the reflash does is if you free rev between 1500-4500 rpm, the engines ECU will slowly return the engine to idle. If you free rev above 4500, the engine will return to a lower speed more aggressively. The noise is harmless and doesn’t affect engine life; just some people find it annoying. We haven’t been able to hear this noise ourselves in a 370Z’s that didn’t have super oil in them so it must be pretty minor, although these Z’s had intake and exhaust systems. Perhaps the best solution if you are bothered by this noise is to turn on your radio!