Just seems weird to me that an entirely metric car would have a imperial threaded port for something as simple as an oil pressure switch. The threads are so close in size and shape it can be difficult to tell them apart, 9.7mm vs 10.0mm and a slightly different curve on the thread taper. As I understand it they are so close that you actually can get the parts to fit together, it just isn't going to make a perfect seal.
I was considering a remote sender, something like this.
German Supply - Parts for VolkswagenŽ Cars - VDO Oil Pressure Sender (Dual Pole) 150 PSI