If like brake fluid atf is hygroscopic the multiple swaps should have soaked up any water. I would check the fluid for any odd consistency after a dozen hours of driving etc. Put a drop of coolant and ATF next to each other on a smooth non porous surface and see if they mix. If they do you're done if they don't you'd maybe need to do another transfusion.

Coolant being mostly water will vaporize when hot. On a hot day and lots of steering it wouldn't surprise me if the temp gets up close to 200F a little "goose" with a heat gun would get it above 100C yet way below temp that is harmful to ATF and boil away any water.

Vacuum will work the same at normal temp. pull a vacuum on the fill cap and any moisture will boil away. Steam is 100s of times lighter than oil and will bubble out quickly.

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2011 E70 • N55 (me)
2012 E70 • N63 (wife)