is a good question but probably doesn't have a clear answer.

BTW, not familiar with MB specs for diesels but for gas cars, Mercedes specs MIN operating temp as 80C. That means ALL MBs will meet their published 'specs'. Note that's the MIN temp.

So, of course, this implies that there is a MAX temp. But that has not been defined. My car runs very efficiently at 90C. I do know at 110C, it lacks pep and you can feel the engine's retard.

So somewhere between 80 and 100C would be "ok". With the CH, I keep my car at 90 - 95C even with A/C on.

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Regards . . . . JimF
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'94 S500 Cpe

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