You can try replacing the low pressure sensor as these do sometimes go bad.
You really want to test the oil pressure. Have you pulled the valve covers?
What does the inside of the engine look like? I have seen really cruded up
engines have true oil pressure problems form the pump inlet screen getting
blocked with crud. These are difficult to diagnose as once the engine shuts
off and cools enough crud will fall off to allow normal pressure when
restarted. Then as the screen gets blocked again the pressure drops. Sucks
as this means a full teardown for the Waterboxer.

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
craig cowan
Sent: Sunday, September 04, 2011 7:08 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: 2.1 Oil light on at low speeds

I plan to put 100 miles on it before an oil change and transmission fluid
change.
I'm still far from that goal.

-Craig

On Sun, Sep 4, 2011 at 1:59 AM, Kim Brennan <kimbrennan@mac.com> wrote:

> Now that you've driven it around for a bit. Drain that oil out, and
> put in
> 20w50 (presuming that this is a water boxer engine). That 15w40 just
> isn't thick enough for the oil sensors.
>
>
> On Sep 3, 2011, at 8:55 PM, craig cowan wrote:
>
> > On my project syncro (which has sat for a long time) I am now
> > finding
> that
> > the oil light comes on and off at Idle once the engine is fully
> > warmed
> up.
> > What's the best proceedure for diagnosing this problem?
> >
> > It's running fresh 15W40 oil and a fresh filter.
> >
> > -Craig
>
>