Mobil will recommend what they want you to buy, or what they think is appropriate.  Do you think they have bothered to determine experimentally which oil is best for a VW waterboxer?  Their logic was probably something like: "What's a Vanagon?  Oh, a Volkswagen?  That's a Euro car, so use 0w-40."

I'd say the Mobil 1 is a fine oil, but use the viscosity that is recommended by VW (in your owners manual or Bentley).

Allan

On Mon, 27 Apr 2009 06:05 -0400, "Chris S" <szpejankowski@GMAIL.COM> wrote:
> Mobil 1 is good stuff and I use it in my Westy.  Do you have an oil
> pressure gauge?  Can you tell me how the 0-40 performs compared to
> other viscosities when hot after 4000 miles of driving?
>
> On 4/25/09, David Clarkson <dvdclarksn@aol.com> wrote:
> > The Mobil 1 site recommends 0w-40 for our Vanagons. Mobil 1 has seen my
> > vehicle through 264,000 miles so far with zero oil consumption that I
> > have noticed. My engine was rebuilt at 168,000 mi. I bought the vehicle
> > with 105,000 miles on the odometer and am unsure what kind of oil or
> > oil change interval the previous owners used. I leave the oil in the
> > engine for 6,000 miles but replace the factory filter every 3,000
> > miles. My 2 cents worth.
> >
> > David Clarkson
> > 90 Westy