Dale,
You may want to ask this question on the discussion forum. I do know that Prestone has reformulated their antifreeze to be usable in all systems. However, I will probably go with Mercedes since it is only a few dollars more and everyone praises it so much. I would also use distilled water when refilling, as it is inexpensive and good insurance too.
Best Regards,
J. P. Mose
1968 250SL
1987 560SL