Best oil? A6 C6 V6 3.0 TDI

['WG']

My C6 is on fixed servicing and the manual recommends 5w40, rather than the allegedly better 5w30 for long life/variable servicing.
Staying with fixed service intervals and irrespective of cost and mpg, which oil is best for the least wear?
Coming up for the 100k service soon, journeys are mostly short, and no DPF.

[Gazwould]

5W30 507.00 is VW's best performing oil .

['WG']

For longlife, but does it beat 5w40 for fixed service?

[Guest 2]

They're the same oil for fixed and LL. Just stick with 5W30. Quantum LL3 5W30 is available from any VAG dealer for ~£25 flr 5L.

[Gazwould]

Thrashes it !

I have proof...

['WG']

Is it not the case that the modern trend is towards thinner oils to enable better MPGs for the sales sheets.
Surely, all other factors being similar, a heavier weight oil would diminish wear, especially in an older engine?

[Gazwould]

Absolutely not it's all about oil quality , oil basestock groups and additive package .

Do you know the actual difference in viscosity between 5W40 505.01 and 5W30 507.00 @ 100°C ?

['WG']

I'd imagine it's quite small. Is there a 507.00 5w40?

[Gazwould]

No , but the margin is so small , a grade ranges about 4 units and there is 1 unit between the two, so 5W30 507.00 is a thick 30 and 5W40 505.01 is a thin 40 .

['WG']

So, it begs the question, should one move to fixed servicing from longlife as the engine wears? And similarly, should one essentially disregard normal operating recommendations for severe?