Uh...it's always been ATF. Again, the CHF reservoir is the only thing you can get now...which is why BMW has the ATF label to mount in the engine bay when you get a replacement reservoir or lid...and if you clicked the direct link to the part database provided in my reply above...the supplemental info for the reservoir specifically says that the label that you mount in the engine bay to explain that the system uses ATF is sold in CONJUNCTION with the CHF 11 S reservoir.
Unless your X5 was once sold in a BMW market close to or above the Arctic circle...it never came with Pentosin CHF 11 S fluid in the power steering system...it's always been ATF.
