Unnecessary Anti-Drain Back Valve. Bad?

[jdevee1]

I just got a '05 Subaru WRX and picked up a PureOne filter for it (PL14460). I got it home and compared it to the OEM filter in the car and it (The Purolator) was much larger.

I started digging around and apparently Subaru change the recommended filter for all of their 2.5L and 2.0L turbo engines from 15208AA060 (Purolators version is PL14460) to 15208AA080 (Purolators version is PL14612) some time in '04. Subaru claims its because of the filters proximity to the exhaust manifold and the higher exhaust temps on the turbo engines may heat the oil too much. The newer filter is physically smaller making it further from the manifold.

Anyway, I went back to Advance auto and exchanged the PL14460 for the PL14612 which is the same size as the filter that came on the car.

The problem is that the PL14612 has an Anti-drain back valve (The PL14460 didn't). The OEM 15208AA080 supposedly doesn’t have one either because of the way the filter is mounted it isn't needed.

Is their any negative effect of having the Anti-drain back valve since it's not necessary?
Will it restrict flow more than a filter that has no valve? Should I go to the dealer and get the OEM filter?

Thanks,
Jeff

 

[Ray H]

Nope. Don't worry about it.

 

[Santo Fontana]

This will probably help: NASIOC thread

 

[T-Keith]

Get the bigger filter with the ADBV and rig up a heat shield for it.

-T

 

[TC]

ADBV's are nothing more than simple one-way valves (flaps, actually). Since there's no good reason for oil to flow backwards, it can't hurt to have one where it's not truly necessary unless it significantly restricts flow. Most filters have 'em, and I've never heard of their restricting flow in any respect, especially considering the 40-90 psi pressures oil pumps can generate (the flaps are easily overpowered).