Are you certain about the <2000rpm claim?  I have a buddy who also drives a vanagon, and when he coasts downhills his buzzer goes off.  (and he throws it in neutral for the downhill coast, so the engine is at idle)

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of David Beierl
Sent: Thursday, December 02, 2010 5:25 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: Oil pressure light comes on after about 7 minutes.

At 07:48 PM 12/2/2010, Roland wrote:
>When I go downhill, at idle in neutral, the light/buzzer go out after 
>about
>7-10 seconds.

The system doesn't operate below ~2000 rpm...

>The next step I am considering is to get some different oil.  I know I 
>am being a bad vanagon owner, but I can't even recall what oil or 
>weight I used, pretty sure it was 40W or close to that.  Probably 
>Castrol or

Suggest drain oil into clean container, put in known oil -- if it cures the problem then you can toss the other oil.  If not then you have some oil to use after the trouble is fixed.  But my nickel is the oil was lighter than you thought.

Yrs,
D