My 2 cents on this issue.  In the aviation world we have a similar mind set.
Pilots think if they lower the oil temp of thier engine then this is good.
It is under extreme conditions.  However your engine is designed to operate
at a certain temperature.  If you lower this temperature (like say 50
degrees) you are not helping your engine but you could actually be causing
damage to it.  So what you really want is a consistant operating temperature
within the range that the engine was designed for.  I think the stock oil
cooler on the 2.1l Vanagon engine fits this bill nicely.
Ken Wilford
Van-Again
John 3:16