> Some Conclusions:
>
> 1) Pressure sensed before the filter.
>
>    This would seem to indicate that the Fram filter is more free
>    flowing than the Mahle.  That actually says nothing about either of
>    the filters effectiveness.  However, the Mahle filter may be masking
>    a bad oil pump, worn engine bearings, or a bad oil pressure sensor.
>
> 2) Pressure sensed after the filter.
>
>    This would seem to indicate that the Mahle filter is more free
>    flowing than the Fram.  Once again, this says nothing about either
>    of the filters effectiveness.  However, the Mahle filter may be
>    masking a bad oil pump, worn engine bearings, or a bad oil pressure
>    sensor.

        Looking on your block, you should see that the 2200+ rpm pressure
sensor before the oil filter and the "idle" pressure sensor after the
filter (it's between the pushrods). However, your block also has a
filter
bypass valve (it's under that big slotted screw head just to the right
of the filter and on the bottom of the block, but this valve is not
going to come into play with a low oil pressure (ie, engine at idle)...

dave