Many would say the same about you.

The 'better safe than sorry' and 'nothing is too good for my baby' are the rallying cries of the over-maintainer. A fool and his money are soon parted.

How are those $800 dealer oil changes working out for ya?

 

10 years/100,000+mi is actually pretty standard among Japanese, German, and American brands. The coolants are organic acid (OAT) based and work in conjunction with a silica packet in the reservoir.

I don't know if this is what Porsche is using in the 991, but if it is then 10 years well within the expected service life. Just keep in mind that evaporation will still occur. Even though the alkalinity stays stable you may still need to top off the system with distilled water from time to time.