I won't dispute the temp. diffs. between Dex-Cool and MB coolant; however, I have used both and I see identical temps on my gauge.
It's possible that your coolant to water ratio changed when the Dex-Cool was installed.
If you really want to see a difference, use water, 2 bottles of Wetter Water and a qt. of water pump lube. The only problem with this is you now lose the higher boiling temp. capability that you get with a 50/50 mixture.
This coolant- to-water thing is catch 22. There are trades-offs.
1991 300-SEL - Model 126
M103 - SOHC
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