If you own a VW, you want the best oil money can buy for that car. One of the current specs is a 0W40 synthetic; it is synthetic because you cannot make such an oil with normal mineral base stock oil.
Volkswagens sludge up for several reasons, the main one being owners not changing oil often enough, the other is the engine design. The factory does not help the situation by recommending 10,000 mile drain intervals.
Mobil 1 makes an oil that meets Volkswagen and other European specs. It is synthetic and had lots of additives to fight sludging.
In short, owning a VW means you don’t just drive into any service station to get your oil changed. You go to one that has VW approved oil (it will say so on the bottle), and change oil twice as often as the owner’s manual calls for. That will avoid any sludging.