I've used these kits on many of my previous cars with good success. They require that you locate and cut one of the heater hoses for the installation of the Tee. The only problem I've ever had was that the cap on the Tee blew off after several years on one car and I had to make due with a cap off of a milk bottle until I got home.
For MB, I'm not sure where you would install the Tee as the heater system seems a bit different. On my MB, I've simply followed the factory service procedure and flushed the system with citiric acid, rinsed, and refilled. If you need a source for citirc acid, I believe I got mine very economically from chemistrystore.com.
'87 560SEL 267K (177K on motor) Blue/Blue
'98 Buick LeSebre 60K (wife's car)
'56 Imperial Sedan 124K
'67 Dodge Monaco 130K (Sold)
'87 Chrysler 5th Ave 245K and going strong (sold)
'73 Plymouth Satillite 175K (sold)
'96 Chrysler LHS 80K (totaled)