Just an additional comment: the M103 factory manual states to oil the threads and under the head of the bolts, but states no particular oil to use. So we could assume any light engine oil I guess. If the underside of the bolt head is left dry, It will gall the aluminum head surface - I know from experience.
Friction in the threaded area is probably not as critical in a torque-to-yield bolt as used here. The thread friction would affect the initial measured torque value, but it's only 50 lb-ft here. Then the major force is done by the 180-degree additional turn, which wouldn't be affected much by any additional thread resistance, since the stretch occurs on the bolt shank, not so much in the thread area. Anyway, clean threads and lubricant are the way to go, per the manual.

ARP does recommend a special lube for their torque-to-final-spec bolts, but they use specific final torque values and don't specify torque-to-yield measured-turn-angle procedures that MB specifies.
DG