12 miles isn't enough to burn off the condensate IMO. The engine has to get fully up to temperature, and stay there for awhile. I suspect you are getting it warm, but not giving it time at that temperature to get rid of the condensation.

It doesn't happen on one trip or over a week, it happens over an extended period.

SeaFoam engine treatment is 70 or 80 years old. It is a very low tech product, and it can be harsh on the internals of your engine. Both the oil additive, and the fuel additive, are specifically recommended against by BMW.

__________________
2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue