For those of you that have “low” temp readings on your temperature gauge:
Replace your sensor. Just found another poor soul that “cooked” his engine
beyond salvation (well, actually, a multi-thousand dollar rebuild job would
revive the engine).
His reading never got above 75C and he was fat, dumm and happy until the
engine croked. He, he 
I can’t thank this list enough for making me
replace my temp sensor. Had the same exact problem. When I replaced it,
engine temperature shot to 95. In my case, I would not have overheaded but
now I know I am observing real temperature.
Can’t own a cat without opening the hood and questioning not only when it
runs badly but when it seems to run ok as well!
Steve Heracleous
84 XJ6 Sovereign 4.2
Reply to: @Steve_Heracleous