The CHF-11s is a synthetic, unlike ATF, so I suspect people are seduced by that word and relate it to quality, thus terming it an upgrade.

The viscosity is different, particularly at cold temperatures. So I could see BMW might have used it to address a specific issue related to cold, or one related to a noise in the pump related to production tolerances with a batch of pumps.

There is at least one post on here with a 3.0 labelled with Pentosin CHF-11s on the reservoir, so it wasn't just 4.8 models. Killcrap made reference once to the fluid being changed, so it may have been a campaign and some vehicles were impacted over a specific serial number range.

All that matters is that people don't mix them. Nothing wrong with the fluid that came in the vehicle, whatever spec it was.

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2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue