UPDATE: Went to see my local dealer on Friday for hopefully a more reliable answer. Spoke to the very helpful service manager who took a screen print from their KSD2 service data system after searching on my VIN...
KSD2 data lists CHF 11S as the default steering fluid for my car, with an alternate fluid of ATF DEXTRON II. So in my case either steering fluid is suitable (but cannot be mixed). And further to this the service manager advised the steering fluid smell can also identify which fluid is in use. Seeing as the color of my fluid is a browny shade, we then went and did the smell test on my fluid compared to that of another car in for service (a 2011 335i) which was using CHF 11S and still had its green 'USE CHF' sticker in place on the cap. Smell was the same, unlike that of the ATF Dextron II which I had purchased a couple of weeks ago which smells distinctly different.
