[doug_porsche]

Every thing in my post may be wrong.

At one time, on a different forum, we had a career tribologists who frequently posted. He not only actually knew what all the numbers in the BlackStone report meant, via his work, he had access (and knowledge) to the machines the produce the BlackStone numbers.

I asked him your exact question, in all fairness it was 10+ years ago, and his answer was...

For an air cooled Porsche, it was worth it to use synthetic.

Todays dino oil is amazing stuff. Even the average quality oil is better than the best oil you could get not long ago.

Todays synthetic is frequently not 100% synthetic.

The advantage, as per the tribologists, was that synthetic is better at extremes (like you said).
It flows better cold, it offers better protection hot.

Under normal usage (for liquid cooled cars, driven in normal usage), Dino-oil is fine.
I have read that under normal usage, if you change your oil every 5K miles, you will never have an oil related failure.

If you use your car outside these parameters, the added protection of a synthetic starts to make sense.

Unfortunately for you, air cooled cars, even when driven in a responsible manner (i wouldn't know how to do this though), asks more from the oil. The oil temps vary more than in a liquid cooled car.

Although you would probably have no issue with dino-oil that is changed regularly, I would spend the extra coin to go with a good synthetic.

Every thing in my post may be wrong.