Pretty sure there's some comments on this forum from way back - Nissan's original "magic 370Z oil" was mineral base with some esters added. If you used a generic oil you'd get lifter/VVEL noise. But I believe Nissan have stopped selling it now and everyone just uses synthetic oil. Bonus points (and quieter) if you're using a PAO ester oil apparently.

Finally managed to pinpoint where exactly my noise is coming from. It's not actually coming the engine compartment but instead it's coming from the transmission area.

According to a mechanic, not an uncommon side effect from my new xtreme twin plate race clutch which in itself makes a ton of noise when I press the clutch pedal down (due to the nature of the clutch design, I've been told).

Plus, it's kinda hard to engage 1st gear smoothly, especially when cold. It's soooo sensitive. I think I've seen a "clutch pedal spring mod" or something along those lines mentioned in various threads. Will try to do a search. I'll need to try it out.

You have the RJM clutch pedal already, right? If not, get it. It will change your driving world.

Thanks! I think that's exactly what I am after. Just couldn't remember the exact name. Will order one soon.