I once put a Primus stove under the oil pan of a gasoline engine I was trying to start at -30F in Battle Mountain, Nevada in 1990. I also put my wife's hair dryer on the intake manifold and covered the engine with the spare tire cover. The thing that worked best was a battery charger, which allowed me to crank the engine every 20 minutes or so until 11:30 AM, when it finally started.

You can temporarily connect a cord to the block heater -- it's just 110 VAC. A stout cord (block heater pulls ~400 Watts) with spade connectors. The block heater should be on the right (passenger) side, back near the block coolant drain. May have a black plastic screw-on cover to be removed. Four hours should be enough [Edit] -- four hours of heating, I mean, not four hours to install the cord.

Jeremy

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970