Not long ago I queried the list about the oil filter-incorporated
Oil/coolant  cooler that many VW seem to have.  My old 1.8 liter Jetta
inline motor in my van did not have one but the replacment 2.0 liter motor I
just installed did.  So I was curious as to whether they actually did
anything...they looked pretty small to me and I figured the temperature
difference between the coolant and the engine oil couldn't be so much that
the 'cooler' would help.

  Anyhow, I had mine running with out the plumbing going to that heat
exchanger/cooler, whatever you might want to call em.  I didn't have any
hoses or plumbing from my other motor and it ran fine without one so...But
since this was a hybrid of two different motors, I decided I really wanted
to KNOW how it was working, inside..so I installed a real (analog) oil
pressure gauge and an oil temperature gauge..and I found my oil was getting
too hot for my liking..Running it at 65mph on a 40 mile highway cruise
showed the temperature of the oil stabilized at about 240f...and the oil
pressure went down as the oil temp went up...15w 40w regular oil running in
air temps of about 75-80f.

  So I plumbed in the coolant lines to the top of the oil filter, the
oil/coolant heat exchanger deal.  It brought my oil temp down by about
35degrees on the same highway drive, same temps outside, same speed...and my
oil pressure stayed up better, since the oil was significantly cooler.  Now
my  oil temp hovers at around 200-205f and my OP is around 30psi at 3000 rpm
(60mph in my rig).

  I was surprised.  So there you go...if you have an old style without the
oil/coolant filter mount and you want to cool down your internals, find one
of the oil cooler filter mounts...they are the same (on my motor) fit..and
bolt right on..

  I will probably add a real oil cooler, too,  for further cooling on my
motor...

  Don Hanson