Rog,
Maybe it helps in Northern Germany or Alaska, but not needed where I prefer to live. It can also block the heater flow if stopped or clogged. Even worse, it can leak from the shaft so you slowly lose coolant and only find out when your engine overheats and is possibly damaged. Anyone who keeps it should fuse it so it won't cause a dash fire if the motor stalls (suspect in some incidents).

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans