I am about to re-install the several temperature sensors to the head. Do I use anti-lock on the threads? I did not see any teflon tape or sealant on them either, but the car is 35 years old, so... (1989 300SE). Please let me know so I so it correctly.

Probably should go in dry. Tape etc. could cause electrical resistance which effectively changes the value of the sensor. If the sensors used aluminum sealing rings/washers, the rings/washers should be replaced.

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer

OK. Great! No anti-lock either then?

I wouldn't...

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer

What about Loc Tite so they stay tight?

Loc Tite not anti seize was really my question. My grey matter...

Still wouldn't, have never had a problem and there is a small chance Loctite could also create a resistance to ground. I'd install them dry and only use something else in the unlikely event there was a problem.

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer

OK. Thank you. Will follow your advice.