Any filter that filters down to 1 micron does not flow as well as one that filters down to 10 or even 5 microns. I think you know how it works more flow, less filtration. More filtration, less flow.
On a turbocharged MK3 its almost mandatory to use a K&N oil filter because of the 1" bolt head on the bottom of it. If anyone has ever tried to get a cheapo oil filter off of their turbo MK3 they know exactly what I'm talking about. I spent a solid hour trying to position an oil filter wrench up there when I first changed my oil 2 years ago but I did, which I bet you can ask anyone else that has tried, and they would say its impossible. Plus I get K&N oil filters for free anyway so its kind of a no brainer. Now oil changes take me 10 minutes total time elapsed.
I also use Mobil 1 10W-30 because, yep, I get that for free too. Its nice to have connections.
