I am spoiled by reading the test results about "coupon erosion" published for the BASF/Glysantin. All I could get out of Prestone was that it "passes the test," of course the test has erosion limits, but it would be nice to know what they are.
I think it would be pretty wacky to run a German coolant in this kind of car though. I know that G48 is easier on solder than some of the others, but I think is a bit harsh on brass. G05 is slightly less nice to solder but does not attack brass.
I filled a G48-spec German car with Dex during an emergency (2001 or so), and left it in there for many years, no adverse effects noted even at the present time.
I think the Prestone will be fine though. Oops. Someone above seems to know better than me. Maybe that's why they wouldn't tell me.