good point
Another thing you may want to look into is that the VK50 motor using VVEL (variable valve event and lift) technology. The lifters in that are more prone to wear which leads to noise when you don't use an oil with an ester additive in it like the Nissan Ester oil or Redline motor oil. The VVEL engines are very demanding from what I've seen on G37's that also use VVEL. The ester helps reduce friction more. The high copper could also be coming from your engine internals wearing alot more since your not using the ester oil. It wouldn't hurt to try it once and report back.


