Noisy CVT transmission experience

First thaks to Cisco for a great site.
Bought a real banger of a Micra last year, was misfiring badly on pull off and had slight noise from CVT, but low km's for it's age (125k), so I bought it as a L plate for son and side project to work on.
The resolder trick on throttle body sorted the missfire and engine ran as sweet as a nut.
However.... CVT transmission noise got worse and worse. Sounding like a jet plane when spooling down to a stop and like a washing machine kakking itself on pull off and low speed.
So I guessed it was electro mag clutch bearing, removed CVT box and replaced bearing. Refilled with Penrite CVT oil, noise went away only to come back after a while- so it wasn't clutch. Also bought a new brush holder- the old one had worn down.
Now it was personal- I had invested a lot of sweat and was getting nowhere...
Then replaced with 2nd hand CVT trans. from Sport Classic's scrap yard (Brilliant spot for 2nd hand micra parts).
Refilled with Penrite CVT fluid and noisey for 10km? then went away, success, or so I thought.
Quiet for about 100km and noise came back after long drive when everything heated up thoroughly.
Next guess was the oil, bit the bullet and bought 5l of Nissanmatic D from Nissan dealer. Drained and swopped (2.0l drained out so still some of the other oil mixed in)
Noise improved but started to come back a week or so later as per last time, this time slightly different, almost as if it was trying to get better but just couldn't make it.
Drained oil again, (again around 2.0l swopped), and after 3 weeks driving gearbox is as quiet as anything- jet plane noise has gone, spin cycle gone.
Nissanmatic D and multiple changes to get rid of old oil has solved the problem. (5l was enough).
I think what happens is that between the steel bands of the belt is a strange environment- need an oil that can get in there and stay stuck in- not squished out as it runs around the pulleys. Previous owner had probably serviced car as cheap as possible (cheap oil maybe even standard auto box fluid)
Hope this experience helps, keeping my fingers crossed that noise stays gone.
Cheers.

Good work, let us know how it goes

Hey guys, thats good to know as im having a similar problem but not quite as bad i only get the crazy spin cycle chain rattle noise when idling or slowing down to a complete stop.

Gonna put some proper oil in and see if that works.