W126 questions: RPM, temp, etc

[Randall Hansen]

Hi folks ~

I just replaced my demised 300TD with an '87 300SDL. So far I love it, but I have a couple questions, mostly where it's different from the W123:

• Temperature: It seems to warm up much faster, but even after 30 minutes on the freeway doesn't get much over 80 degrees. The W123 usually ran at about 100 degrees. That's with and without the A/C, but we've not yet had a day over 60 degrees here. Is this normal?
• RPM: The W123 seemed happiest at about 3100RPM. What's optimum range for this engine?
• Speedo dots: I feel silly asking this; I've been assuming that the little dots on the speedometer represent optimum cruising speed. Or is it maximum speed for a particular gear? Or something else?
• Turbo: The wagon's turbo was really obvious. At about 2k RPM it would start to whine, that would increase in pitch until about 2.2k or 2.3k, then the whine would stop and the boost would kick in noticeably. With the SDL I get very little indication (except that it's much faster than the wagon ). Was the wagon out-of-normal? Is this normal for the W126?
• Flooring it: The advice I'd read about the W123 was, "Baby it until it reaches operating temperature, then drive it like you stole it -- assuming valves, time chain, etc are in good order." Save advice for the W126?

Thanks!