'87 5KCSTQW Coolant Question

["Paul F. Levine" <paulevi@psd.k12.co.us>]

Hello again,

I was just reviewing some records I got with my '87 5KCSTQW a few months 
ago. Apparently, a dealer had recently flushed and replaced the coolant 
with the phosphate-free coolant as per Audi.

In some work done since I've owned it, I realized that one mechanic 
topped it up with regular Prestone and and his ok so did I when I changed 
the radiator thermoswitch.

Is there any grave danger to the cooling system in having the mix. I know 
it is not recommended but I was wondering if anyone out there has any 
first-hand experience or at least knows the science of it all.


TIA,

Paul Levine
'87 5KCSTQW
Ft. Collins CO