you have the identical car
yesterday was 95, and i test drove it, stayed at 90c, ac on or off, highway/city, except when i climbed 1000', then it went to 110, no higher, ac on

since posting, i went all over the forum history, and other sites, and there is much conflicting info(as usual -- was the same experience re:ball joint replacement, which i just finished) -- found several owners who "run hot", with even the same temps i'm getting, and they took it in stride -- but then others who said their temp stays right at 80c, and anything else is unacceptable, requiring flush, etc.
never noticed this issue until this first summer here in nm mountains, so it may have existed for years, since i don't think i would have noticed running at 90c

re: the rad, i meant internally, i.e., looking down into the tubes of the core with the cap off -- i've had rads that were gunked up on other mercedes, this appears clean, as does the coolant when i change it

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78 240d: Mona
81 240D: Lola
77 toyota chinook: Carlito
93 chevy k1500: Cowboy