Greetings! since nobody else seems to be home, i'll just throw in my 2 cents.
if it's available i use Zerex G-05 (i believe it's valvoline product but not sure), which is apparently the same as the MB coolant. not cheap ($10 a gallon), but probably easier to get. recommended for (they say) all MB engines, including cast iron and aluminum.

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rayroyw
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'85 380SE (238,300) my "new" old car!
'84 300D (303,000+)
'72 250/8 (mercy heaven)