Computerized engine management and fuel delivery, a religious maintenance schedule and sensible driving habits.
As Mike pointed out, the normal breakdown of the oils additives and the dirt it collects, are enough reason to change oil periodically. Considering that the oil plays a major roll in temperature management, maintaining those additives is critical to long engine life..
I try to change my oil every 3-5K with any good oil & a WIX filter and I expect my engine to outlast me. I have a friend with a '67 Mustang with a straight 6 that is finally just about due for his second overhaul at 400+ K.
It's a pity that so many people have zero idea of the extreme heat and pressures an engine goes through and how affordable good care of this major investment can be.
my 2¢
