Thanks for the info. I'm back to using the Audi brand coolant, but I didn't for a while. How long does it take for phosphates to damage the engine? In other words, is it instantaneous when the phosphates contact the aluminum, or does it take time -- perhaps over months or years? Thanks, Scott Spangenberg SSpangenbe@aol.com 89 200T 181k mi 85 5 Ks, gone 79 5 Ks, gone