From the 1973 edition of the workshop manual (all emphases added):
Section C14, DISMANTLING PRIMARY TRANSMISSION AND CLUTCH, para 15
Collect the spacer washer or washers used on the centre stud. Note that if a sufficient quantity of oil has drained into the crankcase prior to stripping, oil will tend to run from the chaincase securing holes in the crankcase, thus it is recommended that the bolts be replaced finger tight in the lower holes.
And the opening of section C15, REMOVING CRANKCASE ASSEMBLY FROM FRAME
Removal of the crankcase assembly from the frame ismost easily achieved by removing the remaining ancillary equipment then taking out the front mounting complete and draining all remaining oil from the crankcase
Although the lowest of the chaincase-to-crankcase bolts is quite low, note the reference to âholesâ (plural): the next-lowest is about at the level of the crankshaft axis.
Evidently the factory contemplated the possibility (likelihood?) of significant volumes of oil being present in the crankcase as a normal event.