Using a timer for the Block heater is the way to go. Make sure it will pull the Amps and any extension cord you use will do it too. I think it is 30Amps you need IIRC. A heavy duty timer set for three hours is about perfect. Make sure you drape the Extension cord over the mirror and in your way so you don't forget to unplug before you crank and drive off.

Although I normally do not bother unless I need to get an early start in below 20F degree weather. Anything above 20F I will cycle the glow plugs two or three times before cranking. This works for both my Diesel vehicles.

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1983 300D-Turbo - Deep Blue w Palomino MB Tex (total loss in fire 1/5/09 RIP)
1995 E320 W124 Polar White/Grey Mushroom MB Tex
2005 F150 Supercrew - Arizona Beige - Lear topper
1985 Piaggio Vespa T5 - Black and Chrome

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