You could try downloading the "Comma oil finder" app.

Thanks Andy but you overestimate the amount of service info that VW provide. The oil cap just says Castrol. However the dealer (Inchcape) use Mobil.

The handbook is poor on service detail. it doesn’t have an oil chart where you can read off the spec. It’s just a bunch of text that you need to go through to identify the oil. Even then it’s just (for example) a high level description such as VW 502 00. You then have to Google on general sites to find out what viscosities this covers. I have done this but it’s still an apparently wide range of options. Hence my bemusement at trying to understand what the official manufacturer’s guidance is.

A further routine service example is spark plugs. Nothing in the handbook on intervals for spark plug changes but the dealer site says it’s on the major service ie every two years “if required”. At about £100 a time it’s not the trivial cost plugs used to be. Googling shows that 4 years or 40k miles is actually what’s specified. Thats also what my indie’s database tells him so they are being done this time round.

I know handbooks generally have become less helpful to the DIY’r or interested owner but this is the poorest I have come across for the lack of basic, clear info.

Blimey! You'd have thought that of ALL the things needed, what oil to use would be in the top two (other than tyre pressures), given how crutial they are to the short and long-term health of the car. Whether this is a 'modern thingy' or one of VAG's many qwerks, I don't know.

My condolences.

I know handbooks generally have become less helpful to the DIY’r or interested owner but this is the poorest I have come across for the lack of basic, clear info.

I'm not up-to-date with car handbooks, but that is certainly true in my limited experience of Peugeots. But the handbook for my 207 offers three viscosity grades, which I assume any owner can choose from, perhaps taking into account ambient temperature and season.

Some have suggested that makers are advising thinner oil to achieve a marginal reduction in fuel consumption to get below some EU cutoff line. But I'm not convinced that there is only one magically perfect oil viscosity for each engine. Changing oil (and maybe filter) at proper intervals - not necessarily those in the handbook - is probably a more important consideration.

In fact the thinnest oil in the range I have been offered (0w20) is actually the one that claims the longest life in both time and mileage due to its additive pack. There are also not any horror stories about engine wear from it.
My simplistic view is that good “thin” oil will coat metal surfaces as well as good “thick” oil. For the crucial, high wear, cold starts it’s the thinner properties than offer the protection. I am sure others will have a more scientific view either way.

Thick oil doesn't mean less wear.

Yes.

It does.

Other stuff like additive pack being equal, of course, which you have to assume for any meaningful statement on the question to be made.

Whether the additive pack on these VAG spec. oils IS in fact equal I dunno, but its possible the inherently lower wear protection of the skinniest is compensated for by a better boundary tribolayer for when contact occurs.

OTOH flow rate does not mean lower wear. It means flow rate.