I have both the Mann 719/12 and the 719/5 oil filters in front of me
and although Ken Wilford only sells the 12 as a Vanagon 2.1 filter,
Bus Depot sells 2 Bosch units and two mann's and the Mann's have a
different price.  The  056 115 561 Mann filter(719/12)   is more
money making me think it's the one with the anti drainback valve in
it, but honestly, I look down the throat of the 719/12 I bought from
Ken and I don 't see anything in there resembling a valve.  The  056
115 561 G Mann filter listed at Bus Depot (which is a 719/5) appears
to have something down there that resembles a valve of some sort, but
it's less money.  The Bosch's are about the same price as the
719/5.  Any one researched this or have any insight?  I've also got a
719/30, but it's for a 12Valve Audi and I don't need to make this
email any more confusing than it already is.

I'm pretty sure Ken promotes the use of the anti drain back filter,
but where is it on these 719/12's?