Interesting... I recently flushed the coolant and added the same Zerex G48. On the initial 14 mile test loop, I monitored KTEMP on the OBC hidden menu 7. The highest I saw was 101 C, '04 4.4i N62.

Mine is stock and all original parts in the cooling system. The last flush was at least a decade ago. My mechanic friend, RIP, (BMW master tech) would check the coolant every year and say it was still good.

I got ~1.25 gallons out using my modified radiator flush method. I'll post more on that on my original thread.