almost all filters have a anti syphon valve. the real reason the mann filter stops the red light is it has a very coarse filter media and a very low bypass pressure
so oil gets through by bypassing the filter media. This is just a band aid, the real culprit is marginal oil pressure.
mike

Date:    Wed, 26 Feb 2014 10:50:47 -0600
From:    Dave Mcneely <mcneely4@COX.NET>
Subject: Re: Mann Oil Filter and lifters Was:Engine Starting Problem

Good point.  But, people who deem themselves knowledgeable sure extol the importance of this oil filter feature.  mcneely

---- Alistair Bell <albell@shaw.ca> wrote:
> I've never been clear about what the heck an anti drain back valve does on an oil filter that is pointing more or less down as it does on the wbx.
>
> Maybe it is an anti suck up valve?
>
> Alistair
>
>