"Popular" is not a practical term
In the age of A3/B4 I think that was M1 ESP 5W-30. For finale users. Was, because his availability ends.
Mobil1 is generally "strong" brand in the EU (good old time), but there are BIG problems with falsifications...
In bikes Motul are still unassailable
Popular in (car)companys and industry (as, sold amount / year), I mean thats Fuchs and Total/Elf. Followed by Castrol and Aral (Aral, Castrol = BP) and Shell.
in engine oils are in recent years... a bit... given way (after short Edge Titanium hype). But Castrols gear oils brands Syntrans and Syntrax (for first Syntrax) are furthemore very very strong.
In the EU you think about diif oil choice something like: "Ok what I can maybe take, if I not choose Syntrax?" Mostly a one chose Syntrax
Its like Motul and bikes.
Top-end are few products from Rowe and a couple from Ravenol. In gear and in engine oils. Only technically, for example, Ravenols GL-4+ (GL-4/GL-5) oils are near without competition. Worldwide. But the penetration
this brands are not so big (outside EU) like anothers.