ICQ>

This has to be ridiculous. Brake fluid contains glycols, to be sure, but the compatibility with cooling system hoses, water pump seals, solder, gaskets, etc. is completely unknown and potentially very bad. I personally stay away from not only such home brews but also the very caustic cleaners that can loosen solders and damage fragile aluminum components and rubber seals. I have used these in the past, only to watch my water pump fail within a week or so and experience radiator leaks from solder joints that were never there before. If you regularly change fluid, using a mild cleaner with a full flush using fresh water, you will not have a problem before the radiator reaches its useful life. With fresh coolants, this useful life is probably a function of thermal fatigue.