John, 
Please allow me to differ.
One of the reasons I am not sold on synthetic oils is because dirt gets in your oil at the same rate regardless of what type you run.
On the vanagon its overkill IMHO.
Sorry to differ right after you spent all that cash.
What are you hoping to gain?
better fuel economy?
longer lasting main bearings?
The costs far outweigh the gains if any at all.
The engine temps and oil requirements on the ole simple push rod wbx do not require the benefits of synthetic.
Turbo motors for sure can benefit because of the high heat the turbo bearings run at dino oil will break down.

I have a Porsche 968 and I run standard chevron motor oil I buy at costco and change it whenever it starts to get dirty.
Keeping oil clean is far better than trying to run synthetic longer IMHO.
Its also far cheaper.
I know others will disagree but thats why we have the list.
I have pulled down hundreds of air cooled vw motors and porsche engines and regular oil changes help quite a bit on wear and tear.
Standard oils work fine for standard service.
If you are running an indy car at 12000 things are different for sure.

Doug

  ----- Original Message ----- 
  From: John Meeks 
  To: vanagon@GERRY.VANAGON.COM 
  Sent: Monday, May 31, 2004 7:55 PM
  Subject: Mobil 1 oil change interval

  Hey List,
          Today I changed my Castrol GTX 10w-40 (dino) winter oil for Mobil 1
  15W-50 full synthetic on my 160,000 mi 2.1l Multivan. How long can I
  expect to run it before the next oil change? I'd like to take a survey
  on average oil change intervals for people running full synthetic in
  their WBX engines.
  Thanks in advance for your input.
  --
  John Meeks
  '91 multivan
  Top of lower Michigan
  Vanagon Rescue Squad
  http://www.vanagonauts.com/?catid=74