I realize that it will be hard to do (restore a bit of faith
in GM's engineering), but here is a bit of info on this
particular engine, found in the Impala.

We had one of these apart the other day, it bent a rod
due to being driven thru a large body of water (we had
some sort of flash flood the other day in our city).  Engine
ingested water and bent the rod.

This is the code N 3500 engine, which uses the variable
valve timing (on a camshaft in block design, no less!).
While it was apart, we noticed that GM has completely
changed the design of the cooling system.  The intake is
dry, there are "no" cooling ports in the cylinder heads, and
they have moved to an external water crossover system that
is the same design that the Northstar has used for years.

No more intake related problems on this engine.  At least
as far as coolant getting into the oil.  I took a couple of pictures
of the intake gasket and head gasket.  Just for interests sake.

http://members.shaw.ca/ianrmac/Images/DSC03280.JPG

http://members.shaw.ca/ianrmac/Images/DSC03282.JPG

http://members.shaw.ca/ianrmac/Images/DSC03284.JPG

Note that there is another 3500 engine (code 8) that comes
in the Malibu.  That one does not have the variable cam
timing and still has the older wet intake design.  Why GM
just doesn't drop it and put the code N in all the cars is
beyond me.  Probably need to get rid of the stock first.

So I guess the moral of the story would be to buy an Impala
instead of a Malibu....(if you even want to buy GM in the
first place)

Ian