I'm not big on the 'idiot light' thing but I'm wondering if a reliable audible alarm which indicates temp rising to approx. 3/4ths of the scale might be a good idea. Or even a bright flashing light perhaps. My bimmer gas gauge has a light which catches my attention. I glance at the temp often but it's way easy for it to shoot up before you notice.

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Te futueo et caballum tuum

1986 300SDL, 362K
1984 300D, 138K