There was a good article recently posted about the very long extended coolant change interval in newer MBs. I think it was by Dave M. (GSXR), but that may just be the voices in my head talking.

The gist of it was that new MBs (and replacement parts) have a silica gel pack installed in the plastic coolant tank. The pack constantly refreshes the anti-corrosion components which are consumed out of the coolant. Hence the coolant never 'wears out' as it does at present.

It's a cool idea. I wonder if it works!

- JimY