[C320-list] Where's the oil?

[Robert Seastream]

All:

Yesterday I moved my (2002) boat to the haulout staging area at my  
yard.  This brought the engine up to operating (~160 F) temperature.   
I let the engine sit to allow the oil to drain into the oil pan prior  
to changing it for Tuesdays' scheduled fall haulout.  I checked the  
oil level thrice.  It was a quart low (yipes!), but oil was still  
visible on the end of the dipstick.  I took my 'oilboy' and attempted  
to drain the remaining oil, but surprise, no oil came out!  I replaced  
the filter, refilled the engine with the specified type and amount of  
oil, ran the engine, all's well.

The engine manual states that the 3GM30F holds 2.6 liters (2.75  
quarts) of 15W40 oil.  I'm guessing the little spin on filter holds  
about 8 ounces.  So, 2.75-1 quart (low)=1.75 quarts.  Remove .25  
quarts for the filter=1.5 quarts that should've been in the oil pan.

At no time this season did I get a low oil pressure light or alarm  
(both work), nor did the engine run hotter (160 F) than normal, nor  
did I detect any abnormal engine functions or noises (lack of  
horsepower, acceleration, knocking, smoking on startup or under sudden  
acceleration, etc).  Where'd the oil go?

Robert Seastream
Intuition # 906