I posted a question similar to your a few weeks ago, and someone sent me a link to the Car and Driver web site, where they had an article on the two type. After my reading and research I flushed lightly with prestone flush, rinsed 4 times running to normal temp, cool and drain, then filled with Prestone low tox green stuff mixed with distilled water. My neighbor thought I was a maintenance freak even before I bought a Volvo, but I plan on driving it a long time. My reading on antifreeze determined that it isn't so much as which antifreeze you use, as long as you flush the thing and replace it periodicaly. I did read some bad press on the dex-cool (Orange) saying that older style water pumps may cavitate because of it, but there are additives that are suppossed to fix this. Also, take the time to replace the thermostat, mine failed at 68k and 5 years, it seems to be typical MTBF.

Chuck, 95 850 GLT Wagon NA, clean coolant and a flushed tranny