That's probably it. Be careful unscrewing it. Use a tight 6-point socket, don't risk rounding it off. Once you're able to loosen it, use the other fitting to drain the block of coolant before removing the plug to install a block heater.

Jeremy

__________________

"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .343,000 miles Wife's car
2005 E320 CDI . . 148,000 miles My car
Santa Rosa population 177,300 (2026 projected)
Total. . . . . . . . . . . . 668,300
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970