[romanzdk]

A week ago I changed transmission fluid. About 2.4l came out, I put 3l in and then about 0,5l drained out via overflow plug. Since then I done like 300km. The problem is mainly when it is cold outside - the 2-3 gear is a bit “choppy” / laggy. After 10mins or so when it is more warm it seems better.

Is this normal behaviour? If not what can be done about it?

2019 20iX, 80k km, Aisin GA8G45XAW, used Febi Bilstein 183413 (83222413477)

[mDrive1]

I had the same thing when I changed the fluid for the first time. I added ~250ml over the overflow plug limit and the shifting became smoother. I use Liqui Moly 5135 ATF Additive or just transmission fluid will work. no worries, the excessive amount won't damage anything.

[romanzdk]

Isnt is about density of the oil? When the oil is cool it is more dense and therefore the shifting is more harsh (difficult to switch in dense oil)? When the oil warms it becomes less dense hence easier shifting. In this theory adding more oil should not help probably? Also is there really no risk in adding more oil than there should be? I am even thinking of putting there less oil instead of more. I do not know..

[mDrive1]

no doubt about viscosity. at the same time, the volume of the liquid also increases when it warms up. I change annually and have found that I have harsher downshifts, especially from 5th to 4th gear if there is less fluid. Your situation, of course, may be different.