Hi,

  While changing the oil and filter yesterday on my 85 Chevy Caprice,
I noticed something strange.  I always thought that oil flows into the
small outer holes on the filter and then trrough the filter media,
then out of the filter back into the engine through the large pipe
onto which the filter is screwed.

The strange sight I saw was that on the filter mounting plate, on the
engine, what was supposedly the INLET hole had a spring loaded valve
in it.  The valve retracted as I pushed it in towards the engine.
There was no other hole anywhere on that mounting plate except for the
big hole in the threaded pipe.

Since there were only 2 holes, obviously one is for IN and the other
for OUT. Since the hole with the spring loaded valve will only let oil
INTO the engine (not into the filter), then the flow must be :  from
the engine into the filter via the big threaded pipe, through the
media, and back up into the engine via the spring loaded valve, which
must be an anti-drainback valve.

Is this the normal flow direction for a chevy 305 engine?   Reverse
of the usual ?

Thanks in advance