Leaving a block heater on all night is a waste of money ... 10.2 cents/kwh now for me in SE OHio.

I don't have a block heater and don't really need one. It will start down to 10 degrees without any help, but below that it seems the fuel thickens up and won't start. so i put a big light bulb (300 watt halogen) in the engine compartment (in safe place of course) on a timer a few hours before startup and that keeps everything just warm enough.

if it weren't for the fuel, i think the thing would start well below zero.

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1981 Mercedes-Benz 300SD ~285,000 Miles