A high quality oil for sure. I assume it's rated BMW LL-01. If so the OLM on my BMW would recommend a change after about 25,000 Km. The BMW shop foreman advised changing it half way through that interval, so say 12,500 Km = 7800 miles. It comes out very clean after that interval (for whatever that's worth).
Assuming you don't have an especially needy engine, a reasonable interval would be around 7500 miles.