I firmly agree with the last two (three?) posts. Starter motors are hard on batteries anyway and diesels are especially hard because of the high compression. That's why most Mercedes come with that huge battery. Anything you can do (like always glowing) to make it easier on the entire starting system is worth it, IMHO.

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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