>The filter stays full -- but the oil from higher points in the engine
>drains back through the filter.  Points like the valve train...

Uhh, see that's a little reason I don't really buy the importance
of even the antidrainback valve on a waterboxer, what valve train?

There is not valve train above the location of the filter on a T4 or
waterboxer, one pressurized oil gally, and it's not like it will hold
pressure.  On the inline 4 that filter is made for, sure, makes a hell
of a difference keeping stuff up in the hydraulic lifters, on a waterboxer,
I don't think so.  Makes one wonder if using an open can style filter
without the valving and with more filter media might not be a better
idea.  T4's don't have anything in the filter, and my hydraulic T4's
clatter no worse than my hydraulic waterboxers, all the valve gear
being well below the filter.

Now there was talk of siponing prevention, and that I don't know,
would have to give it some thought.

John
jander14@wvu.edu