You don't get an "MB-Approval" on an oil bottle unless Mercedes Benz has approved the oil, it says it clearly on their website. There is a difference if you see "MB 229.3" versus "MB-Approval 229.3"
Die Mercedes-Benz Betriebsstoff-Vorschriften zeigen eine Übersicht der Anforderungen der im Fahrzeug benötigten Betriebsstoffe und der empfohlenen Produkte. Betriebsstoffe sind alle zum Betrieb eines Mercedes-Fahrzeugs / Aggregats erforderlichen Flüssigkeiten bzw. Schmiermittel z.B. Kraftstoff...
bevo.mercedes-benz.com
While motomaster currently cannot be found on their lists, there may be a few reasons.
a) they haven't updated their list yet to include motomaster, as it's still a relatively new oil on the market (the rebranded version that is, which came out sometime last year)... It's true that the most recent update of the list is March 5, 2021, so I am curious why they haven't put it on the list yet.
This leads me to propose option b)
Motomaster isn't actually approved, which would then be false advertising on the bottle, as it's clearly labelled "MB-Approval 229.3", versus MB 229.3 like on the supertech 5W-40 sold at walmart
I'm sure Mercedes would like to know if an oil company is stamping "MB-Approval" on their bottles without being allowed to... If it's true that this oil isn't Mercedes approved, there would likely be massive complications involved
So if it is approved by MB, which I comfortably believe it is, then it's good enough for a VW with 502/505 spec
Also, please show us your virgin oil analysis on how this oil didn't meet the specs... I have been running it in an old ALH and my engine hasn't blown up yet... I plan on doing an oil analysis eventually to see how this oil holds up, but i'm not concerned one bit. It's frustrating when vendors claim something is crap without actually providing any evidence
Just because it isn't brand name, doesn't mean it's crap... so please back up your claims