Hi guys,

I'm from Australia and this new sound starting come from what I presume is the CVT.

https://vocaroo.com/i/s1Ed5G9tCCPD (around the 12 sec mark)

It only happens when the car has been sitting for awhile, say overnight or +5-6 hours. It occurs around the 40km/h mark consistently. If you're familiar with these CVTs there's like a "shift up" around this stage (i know there are no gears but there's definitely some kind of change in the transmission here).

My car went for a major service (80000km) around the time it started occuring. I had a look at the log book and it mentions the CVT fluid would have been checked.

Any ideas on what this is?

Update: I have taken the car to two different mechanics who have been unable to reproduce or diagnose the noise. I took the car into a Nissan dealer who did a transmission flush but the sound is still there.
Does anybody have a suggestion what it is before I go the stripping route?

I'm not sure. It seems like a CVT sound to me. Having a service done and then getting the sound would make me think that. I know the CVT is pretty picky about fluid levels and type, so if they screwed up, it could cause a noise like this. But, if you can't get it reproduced, it's very tough to diagnose. Two mechanics and a dealership not knowing makes it tough for me to think someone way over here will know, but maybe. Perhaps the right person needs to hear your sound clip and will write a response.

I have heard to install an aux cooler