Got some maintenance work done on my Vitz 2012 last week.
Starting with CVT oil change.
For gear oil aka CVT oil change plz try to read a forum on CVT oil change for Toyota Belta Vitz Passo etc and try to find @xulfiqar bhai's posts in that forum.
Either you can go for opening the chamber approach or draining it via drain hole approach.
I went for changing oil via drain hole approach. Allen key which our common mechanics call "L key" is used to open it. After opening that nut or screw, same Allen key is used to remove the tube that is inside the chamber. Here is the tricky part, most of the mechanics including ones at 3S do know how to take that tube out but they prefer not to, as changing the oil via that bolt doesn't pay well. Usually they try convincing you that opening the chamber is must. Tell the retards that engineers who made the car are way better than them and they didn't put the drain hole and inside tube just to check oil level.
To be sure exact amount of fluid that comes out, ask the oil guy to collect it and measure the quantity of drained oil. Put back same amount of oil.
On the other hand if that's not feasible then after draining the oil put back the plastic tube into the nut hole. Do not put the screw or nut back in its place, just the tube. Put the oil via nut hole in upper part of chamber (don't remember which one is it but oil guys usually know it). When oil starts dripping from the hole, wait for it to stop. Start the car and put it in D. Again pour oil till it starts dripping again, it will roughly take 200 to 300 ml of additional oil. Alternatively you can put the screw back after the oil had initially started dripping and add roughly 200 to 250 ml of extra oil. That's it.
No need of anything else. Car will take back total of 2 to 2.5 L of CVT oil, nearly exactly the amount that was drained.
P.S. Plz don't be confused when u find someone saying it takes total of 6 or 7L of CVT oil, that's only done when you build the transmission from zero. You can't drain the whole oil, just 2 to 2.5 L of those 6 or 7 L are drained and that's what u put back in.
Also opening the chamber technique would require roughly 3.5 to 3.8 L of oil.