Just came accross a letter authored by this fellow Bryan Moores. The letter is in response to a question asked by a service director in VA. It is dated
1/24/07, with a subject entitled, Radiator White Substance. It goes on to talk about how they are aware of the issue and reccomends that the system be flushed and so on. He goes a step further and suggests that the reservoir and cap be replaced. He is supposed to be a regional or east coast tech advisor.
Don't know if that points you in a direction or not.
Roy