Seems his engine did not like thick oils, but also thin oils too (approved by the way). Maybe position of the moon and stars did not align well too.
Viscosity tailoring is done by race teams to be competitive. Read about it on MOTUL site in the 300V oil section.
"Approved BTW" doesn't mean you are not being "guinea pigged" as VAG treads new waters
Engine oil: "Not so thin as to make destructive noises, and not too thick as to throwaway power and torque"
It's pretty simple.
Maybe some are too lazy to care, or are just careless, or have no ability to perceive.
And it is undeniable the VW is pushing the envelope to the MIN on the 508 000 spec.
Looking at the reported HTHS and KV100 of typical properties is telling:
RECOMENDATIONS Drain interval: according to manufacturers’ recommendations and to be adapted to your own use.
MOTUL SPECIFIC 508 00 509 00 0W-20 can be mixed with synthetic or mineral oils. Before use always refer to the owner manual of the vehicle. PROPERTIES Color Visual Green
Viscosity grade SAE J 300 0W-20
Density at 20°C (68°F) ASTM D1298 0.833
Viscosity at 40°C (104°F) ASTM D445 38.5 mm2/s
Viscosity at 100°C (212°F) ASTM D445 7.8 mm2/s
Viscosity HTHS at 150°C (302°F) ASTM D4741 2.5 mPa.s
Viscosity Index ASTM D2270 179
Pour point ASTM D97 -52°C / -62°F
Flash point ASTM D92 222°C / 432°F
Sulfated ash ASTM D874 0.79% weight
TBN ASTM D2896 8.3 mg KOH/g