Soldato
Not sure why the focus on silicone free? The bigger reason to use the BMW screen wash is it's that not using it frequently ends up in the washer pump filter clogging with a congealed mix of cheap screen wash + bacterial growth (due to reservoir location near heat in most BMW/Mini engine bays) etc.
The BMW screen wash is a strong alcohol base as I understand that prevents any growth, but doesn't mix well with other screen wash.
BMW state that it’s the silicone which can cause build up and blocks the pump system