Most likely a wiring issue as Dennis stated.  A bad sensor would be bad all
the time.  A chafed wire will touch when you are at a certain rpm that
allows it to ground out.  That is why it flickering going down the road,
but not at idle makes sense.  Believe me if you had low oil pressure at
road speed, you would definitely have it at idle when you slowed down.  If
you really want to know what is going on, installing a pressure gauge is
the best way.  Then you can just ignore that stupid light the next time it
decides to go crazy on you.

Ken Wilford
John 3:16
www.vanagain.com

On Wed, Feb 19, 2014 at 5:54 PM, Steven Shelton <shelton4@gmail.com> wrote:

> We left today in our 1985 1.9L Westfalia for a one week camping trip when
> about a hour from home in Interstate traffic the oil pressure lamp started
> flickering.  I pulled over and checked the oil.  If anything it was over
> the full mark.  The engine sounded fine so i took back roads to get home.
>  The light stayed off at slow speeds or stop and go traffic, but at
> sustained speeds above 45 or 50 it would flicker, sometimes quickly and
> other times slowly on and off.
>
> The Castrol 20W50 oil only has about 1,500 miles on it, but it's been 6
> months since it was changed.  I'm changing it now.
>
> My question is, can there be a problem with low oil pressure if the light
> stays off at low RPM?  From what I've read, it seem like when oil pressure
> is low the light is more likely to come on when the engine is idling, not
> when it's running at 50-60 MPH.  The engine is VW rebuilt 8 years ago with
> 54,000 miles on it.
>
> Besides the oil change, the only other thing I can think of is to check the
> wiring at the sending unit when the engine cools down.  Is there anything
> else I can do before we try to leave again?
>

--
Thanks,
Ken Wilford
John 3:16
www.vanagain.com