I have to think that oils like almost everything else, have various compromises. So even manufacturer's recommendations may NOT specifically be to create maximum engine life/minimum wear. They could be specified for other reasons (like fuel economy).
Some manufacturers may recommend different ranges for different regions/countries. Some manufacturers may also have multiple recommendations for one location.
For instance, this is a screen shot of the 987 owners manual.
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Steve
'08 Boxster RS60 Spyder #0099/1960
- never named a car before, but this is Charlotte.
'88 targa
SOLD 2004 - gone but not forgotten