Funny, how our preferences has been changed...
20+ years ago 5...10W40 was assumed as thin oil because all used thick 15W40

With upcoming popularity of 0...5W30 those were assumed as thin oils.

Now we call 0...5W30 thick oils because thin oils now are 0W12...20
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ACEA C5 is typical for 0W20 508.00/509.00 oils and this leads to HTHS viscosity ≥ 2.6 and < 2.9 mPa.s
ACEA C3 is typical for 0...5W30 504.00/507.00 oils and this leads to HTHS viscosity ≥ 3.5 mPa.s
+ thin oils (may) have higher Noack volatility, which (can) lead to higher oil consumption.

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So, if it's totally not forbidden by VAG to use 504.00/507.00 oil instead of 508.00/509.00, for total engine protection (with loss of 1 glass of fuel per each 100km) I would stick with ACEA C3 504.00/507.00 oil.

In Europe's climate / in winter anything with 0...5 before "W" is absolutely fine and far enough.
And anything with 30...40 after "W" will be even better in summer/high load/traffic jam etc when oil is >100*C constantly (instead of normal 90...95*C).

9 hours ago, OccyVRS said:

Just because I'm helping my bearings by using a thicker oil, doesn't mean I'm helping the cylinders, oil pump, channels or whatever else.

Bearing wear might be given over importance but that'd be another great debate, as I put I lean towards 0w30 but could be persuaded to 0w-20 (by other than VW I'm afraid).

8 hours ago, bigcar said:

On the service plan I have the oil is changed annually or in my case every 3000 miles.

Annual mileage that low might well necessitate annual changes at least, that's not the sort of mileage that's always helpful but I've know old cars with lower annual mileage, though I'd not trust this with a modern car particularly something like a VW. I'm with you I prefer extra protection from oils above the minimum required standard (mainly or when something else goes wrong on old cars but also for spirited driving when wanted and possible). I'm helping change the gearbox (and rear axle) oil on a mate's car and I've managed to persuade him to go with a better quality gear oil to save having to do the change so soon again. He previously used an oil that meets the manufacturer's specification but it wasn't that long ago and it needs changing again, a known issue with the gearbox.

For decades now having had various old over-priced, over valued cars called "classics" I've dealt with oil beliefs and know like other beliefs most stop with what they're happy with and feel reassured by and that's fair enough as science has fashions and changes with tim and makes mistakes and frankly sometimes lies (it's not just those at VW) so who really knows who right and when and what's good for one may not be so good for another.

In the old days when I was a young girl and it was all fields around here I knew of people who never or very rarely done any service work on their cars and they carried on working for many years so possible a much more money, time and hassle saving and efficient way of car ownership but I can't see getting away with this for so long with more modern cars.

Even experts don't agree so expecting this with a general population of car owners is optimistic.

41 minutes ago, indars said:

thin oils now are 0W12...20

0w8 to 20, what VW have finally got to is like syrup. 😄

I'm much more used to 20w-50 engine oil and been using (fully) synthetic oils for decades despite being told they would destroy my engines (by people who barely used their "classics" when I used mine as dailies, the oils offered additional protection from all the other cooling issues and overheats rather than destroy the engines.

1 hour ago, nta16 said:

0w8 to 20, what VW have finally got to is like syrup. 😄

I'm much more used to 20w-50 engine oil and been using (fully) synthetic oils for decades despite being told they would destroy my engines (by people who barely used their "classics" when I used mine as dailies, the oils offered additional protection from all the other cooling issues and overheats rather than destroy the engines.

0W8 thks! Before writing I tried to find lowest "second No.", as example- but You went further hehe.
20W... is not really suitable for Latvian climate since we often got -5...-20*C in winters.

But for tuned/race/hot climate those oils xxx W50...60 is must have- taking in mind construction of engine and execution of exhaust gas treatment system

(those type of oil almost never have manufacturers approvals and we don't want to kill Pumpe-Duese / GDI / DPF tuned engine with conventional oil, chosen just by viscosity)

11 minutes ago, indars said:

20W... is not really suitable for Latvian climate since we often got -5...-20*C in winters.

I've used 20w in say -10c winter, it goes to -15c, but to use it in these temperatures is another reason to have a good quality (synthetic) oil which I did, and for fast road use in summer usually not more than 30c here but we have had 41.2c IIRC.

Don't get too hung up on the raw numbers and generalisations, the oil needs to be suitable for your engine and its use and environment but no I'd not be using 20w-50 in my wife's 2015 VW engine.

Bump for the OP. @OccyVRS

Edited 5 April5 Apr by Evolution13