My understanding is that the system needs to be completely free of glycol-based fluid before converting. I would imagine this to be difficult to accomplish witout replacing at least some components.
Compatibility with ABS is suspect.
This was posted on a BMW board from a Teves rep:
">Subject: Brake fluid/E ABS bleeding
>Following are comments from an ITT/Teves (OEM brake supplier) employee
>to questions I posed on Ate Super Blue brake fluid and bleeding the E36
>brake system with ABS. Thought the list might find it interesting...
>********** Message follows **********
>Date: Fri, Jan 13, 1995 1:0 AM PST
>Subj: 3-series brake info.
>Ate brake fluid is glycol based. We at ITT take a rather dim view of
>silicone based brake fluids; the compatibility between your ABS and
>silicone brake fluid is not the greatest. It turns out that the
>hydraulic control unit of your ABS was designed to work with
>conventional (DOT 3 and DOT 4) fluids; silicone fluids can affect
>the sealing performance of some of the internal valves over time. By
>the way, the same applies for other ABS units (Bosch, etc.) too:
>Use only DOT or DOT 4 brake fluid (DOT 5 is the silicone fluid).
>DOT 4 is similar to DOT 3, with the only real difference being a
>slightly higher boiling temperature with DOT 4. Any brand name DOT 3
>or 4 fluid is fine. The newer the can, the better, and don't leave
>the can open in your garage -- it will soak up moisture from the air.
>(That's why you always see the warning "use only brake fluid from a
I also saw this article in my travels: