Good you didn't booger the bolt head by just pulling on the breaker bar. Whenever using a long socket (or extension), put one hand on the socket end of the bar and the other on the handle, then push & pull with equal forces. That applies a pure "couple" to the bolt with no tilting force. Similarly, you could use a 2-handle breaker bar (post 8), like the one in my 3/4" drive Harbor Freight socket set.

I've only removed one OM617 head. I bought a special socket tool (1/2" drive, $18 I recall). It has a shaft about as long as yours. I recall it was termed "double square" (8 pt?), but maybe "triple square" is correct which suggests 12 pt. There are normal 12-pt female sockets, but perhaps as a male tool they don't term it "12 pt". I recall seeing that later M-B engines have more common 12-pt "male" bolt heads which take a normal 12-pt socket (female). 12-pt bolts are common in aerospace components, probably because they save a little space and weight and perhaps can handle more torque. It was a bit scary loosening the head bolts, wondering if the high force would strip the bolt head. Might have taken 90 ft-lbf to loosen. If a bolt head got boogered, you might drill off the bolt head, remove the engine head, then remove the bolt stub with vise-grips.

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans