Help w/oil leak on 4kq

[Jpinkowish at aol.com]

Hi Folks,
I've got this nagging oil leak primarily near the front of the engine along 
the driver's side(USA) just where the oil pan meets the block.  The whole 
driver's side of the oil pan is coated with oil, and also the first few 
inches of the block(to just past the height of the oil pressure 
switch(sensor?)) above the block/pan interface.

This may sound like an obvious oil pan gasket failure, but here are the 
specifics:
--no dripping onto the ground when the car sits overnight.
--pulled the upper cam belt cover and looked down into the the front crank 
seal area.
  The whole inside area is oil free, and no oil appears on the bottom outside 
of the
  lower cam belt cover.  This should mean crank oil seal is OK, yes?
--regarding the oil on the side of the block: will the air moving through the 
engine 
  compartment cause this?
--replaced the TB/water pump 20k miles ago.  Did I not properly tighten a 
bolt 
  somewhere?
--finally, can the oil pressure switch fail and leak oil?

More data needed?

Look forward to your diagnostic replies.  Thanks.

Jan Pinkowish
'85 4ksq
Bristol, CT