That is the most informative study on coolant on the web...
Info on Zerex G-05,
-Zerex G-05 is a low-silicate, low-pH, phosphate-free, pre-charged formula that is designed to protect automotive and diesel engines from rust and corrosion. Zerex G05 is approved by Ford and by Daimler-Chrysler for worldwide applications including all MTU and Mercedes engines
-Utilizes hybrid organic acid technology to minimize inhibitor depletion. (<-- the main reason why you can only use BMW coolant... besides this stuff)
Use this stuff..... its G rated better than BMW coolants G48 european rating.