Technical noisy 5th :(

[Pandaki]

Hi there!
Went out for a ride with the panda the other day and I noticed a whining/whistling noise when I engage 5th. Could that be because the weather is getting colder? Or is it the beginning of a gearbox failure?
I remember noticing that sound last year when I was driving from Venice to Milano but it only lasted a few minutes and then gone until 3 days ago and now it is there every time I engage the 5th. Also when engaging what I hear is not the usual... and actualy doesn't sound good at all. Can i do smthing before its too late? I'll check the oil level in the wkend and top up if nesecery. I changed the oil last year and I used the tutela zc90. Can this be a problem if it mixed with other oils in the gearbox? Does anyone now if the box is different in anyway from the early mkII to the later ones, so the oil I used is unsuitable for some reason?

 

[CLXCraig]

I get the same noise too, but it is only apparent when foot pressed on the accelerator pedal. solution, turn the stereo up!

 

[Blurredman]

Maybe its because you don't use it often?

Is it when you have put it in 5th or in the process of changing gear?
If its in the process I think its normal-Its the gears spinning-