To be honest, I don't know why too.2226 wrote: ↑Tue Dec 05, 2023 6:42 pm I'm aware of all of that.
Polo here is all fixed service interval so 502.
504/507 can do, I know that.
But what I'm getting at is that these VW grades do not cover viscosity of oil, so you can get 0W-30 / 5W-30 / etc for 502, 504, 507 and so on.
For me, it's going to be Ravenol VMP in 5W-30. It's both 504 and 507 approved. I have no need for a 0 weight oil. I'll run on shortened fixed interval. TBN of VMP is lower than my current VST, but should be good over my shorter fixed interval. We will see.
I've seen them testing Mobil 1 oils with the latest Dexos certifications. Those Dexos oils should line up with these newer VW 508, etc. The results were amazing. They can deal with so much more stress and they definitely put down way less deposits in the ring lands. But they are often thinner oils.
I'm amazed they're listing the CJZD as being able to use 508 from 2018 onwards. What changes were done to the CJZD and what vehicle was that in in 2018+?
As for the dealer ... they're all like that here. My problem is I tended to trust them and that nearly cost me this engine. No oil change at last service with them; didn't even bother to check the level. And neither did I thinking they'd actually done the job.
Ravenol is a excellent brand.
You can also consider Wolf, ENI and Shell. Mobil is also excellent.
With an oil like "0W" it means (and I suppose you already know it) oil is thinner at lower temperature. Which means a better lubrification for sensitive components like turbo, camshaft on top of the engine during cold weather.
TBN for my Shell is something between 8.1 and 8.3. So pretty high and almost equal to the 508 requirement (8.1 minimum).
"I'm amazed they're listing the CJZD as being able to use 508 from 2018 onwards. What changes were done to the CJZD and what vehicle was that in in 2018+?"
CJZD was produced after 2018 ? It's a question because I don't know.
If it's the case, I suppose they change some internals components and reduce the tolerance on the machining process. I guess...
Maybe you have to consider the fact of changing of dealer.
Each time dealer give me back the car, I go out with them to check if everything is correct.
Fun story, my grand father is running a Renault Twingo. Good car, very reliable.
On the last oil change, they forgot to tight the oil drain plug...and fall of during the night, and all the oil drain out in the car's garage...^
"Trust but verify"
) has detected your unnecessary haste in your hiperconnected car. 
...and I'm not kidding.
