I use two good fluids, and alternate them so I can tell the difference between the new and old when I flush it.

Valvoline Synpower is either DOT4 or 4+.

ATE/TEVES Superblue would be DOT4+, except blue fluid doesn't meet any DOT spec, DOT brake fluid is clear or amber. (ATE is a major supplier of MBZ brake components)

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'79 300SD W116
'86 190E 2.3-16V W201
'92 300D 2.5 W124
'99 E320 4MATIC S210