Which Oil Filter for 2004 Forester?

[y_p_w]

Hi,

Are you sure you're not thinking of the bypass valve--that would be
metal at the bottom of the can (closed end), where the anti-drainback
valve will be a sheet of neoprene-silicone-other rubbery stuff that
covers the intake holes of the filter at the base (open end.) AFAIK, all
current filters have some kind of a bypass valve, not all the
anti-drainback valve.

I know what a bypass valve or ADBV looks like, and I think Mr Hayes
does too. However - he can clarify given your description. Some
claim that the ADBV keeps oil from draining out when the filter is
mounted (more or less) sideways; I've heard that it can leak out
overnight. Backflow crudding up the oil pump sounded like the best
reason to use an ADBV. I'd guess that oil flow would be marginally
better without an ADBV.

As for the bypass valve - some cars don't have it in the filter.
An ACDelco PF47 (or equivalent) for my dad's '96 Buick Regal has
none. I think the car has a built-in bypass somewhere near the
filter mount. This was the same for another the AC PF52 filter
I used on a Chevy Lumina APV minivan. There was a previous version
(AC PF51) that was identical except for no ADBV. Both the Buick
and the Chevy had the base pointing up, so gravity keeps oil in
the filter.

As for bypass valve designs - I've seen a whole slew of different
kinds:

1) Cheesy Fram design with a piece of plastic and a spring.
2) Metal/rubber with spring at the end.
3) Metal/rubber bypass surrounding the outlet (Wix)

A newer Champion Labs design has 6 holes at the far metal endcap,
with a large piece of metal covering the holes on the other side.
I'm not sure what's at the other end, but I would assume some sort
of spring and/or a gasket.

 

[Edward Hayes]

I will go to the source for an answer and post back.

 

[y_p_w]

That's the bypass valve (if the oil's too viscous or the filter's
plugged, it'll allow the flow of oil to bypass the filter element).
Anti-drainback valves are usually neoprene (or perhaps silicone
rubber?) flaps that deflect to allow oil to flow into the filter under
pressure, and cover the inlet holes when there's no oil pressure to
prevent the filter from draining.

Fram tends to use silicone, although I think their design is too
thin (I've heard of them folding over). ACDelco and Champion Labs
like to use black nitrile rubber.