It's marketing blah...blah.

Typically, oils marketed as "high mileage" don't meet some aspect of
the new car oil spec.  It may be that it doesn't meet the spec to
qualify as "energy savings".  Or it may have more anti-wear additives
then the new car spec allows because new car specs continue to allow
lower and lower levels of various additives that can foul the
catalytic converter and they are required to warranty the converters
for longer and longer lengths of time/mileage by the feds.  So the
reality is that you may get a BETTER oil for preventing wear when you
choose a "high mileage" oil then if you choose the one that is the
latest and greatest spec for new cars.  This lowering of allowed
amounts of anti-wear additives is why you are seeing more and more of
the new car oil's becoming semi-synthetic - they can't get them to
have sufficient wear protection with just dino oil and meet all the
other requirements for reduced additives, etc.  I think you are safe
with any of the Mobile One products. If you have a newer car and plan
on keeping it for a long time don't use the "high mileage" oil if you
wish to make your cat converter last as long as possible.  On the
other hand, if you really want to maximize anti wear protection and
are willing to maybe have to replace the cat at some point, then the
High Mileage oil may actually be the best choice.