GM had some similar problems a while back with their (at the time,) exclusive Dex-cool coolant. Quite a few coolant related problems and lots of angry and perplexed customers. IMHO, this was all a matter of poor engineering. As a whole, I'm still skeptical of the whole "extended" life coolant...
couple of good links on electrolysis:
http://www.drivewerks.com/Newsletter/vol-7.htm
http://www.4s.com/fourseasons/tech_tips/tech_tips_english/AB350_Electrolysis_02.pdf
http://acdelcotechconnect.com/pdf/tsb/tsb_04D-J-051.pdf
denvercruiser,
that's a tough spot you're in. i agree for the most part with what your mechanic has told you. (i'm a mechanic by trade as well.) i don't however advocate "the quick fix and then sell it to somebody else" concept...bad karma.
if your freeze plugs are rotted out/leaking, the...