Personally, I renew brake fluid on all of my vehicles on an annual basis (more or less)......your Benz will take about a Liter/Quart......I also use Valvoline Synpower Dot 3 & 4.......it's easy, just suck it from your caliper's brake bleeder with your MiteyVac, and most importantly, keep the reservoir topped up as you do this.....I begin at the furthest wheel from the master cylinder......you may get a bit of bleed air from the bleeder screw threads, a dab of clean synthetic grease around the beed screw will stop this....

SB

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Diesels:
'85 300D, "Max, Blue Benz", 155K, 27.0 MPG
'84 190D 2.2, "Eva, Brown Benz", 142K, 40.2 MPG
'77 240D (parts car)
'67 Eicher ES 202 Tractor "Otto" (2cyl, Air Cooled, 30HP)
Gassers:
'94 Ford F-150, "Henry", 170K (300 Six) 17.5 MPG
'85 190E 2.3, 148K....Parts Car
'58 Dodge W300M Powerwagon (Flat Fenders) Less than 10 MPG