Jim from BusBoys describes his temps before and after oil cooler install.
Jim, your point about the temp coming right down after peaking on a hard
uphill pull is one of the most reassuring things about a front cooler.
Before cooler, once the temp went up it would take forever to come down;
with cooler, not only is the peak temp lower but the duration is much 
shorter.  I highly recommend a well-designed oil cooler add on for any
air cooled engine that has to work hard in the summertime.
B.